Saiyans tend to share common personality traits, even at young ages. Being war-like people, they share an innate enjoyment for conflict and fighting, choosing violence over peace with other races. Even Goku retained his love to fight after his amnesia, but satisfied that love through competitive sport, rather than barbaric slaughter. Saiyans are typically very aggressive and hard-headed, with short explosive tempers. Saiyans appear inclined to be arrogant at times, leading them to allow enemies to gain advantages in battle just for fun. It appears they have a tendency to let their emotions get the better of them when roused in stimulating situations (as demonstrated by Vegeta, Nappa, and Bardock), resulting in them at times making rash decisions. Normally, Saiyans do not have much of a notion of romance or marriage, and apart from the royal family of Vegeta, they are not particular about blood-relationships. They appear to lack sympathetic emotions as though by choice rather than by nature, as shown by their relative lack of fear of death and uncaring attitude towards family members (example being Raditz's brutal beating of his long-lost brother Goku, and Vegeta's seeming indifference to his father's death). Clearly, neither Vegeta nor Nappa showed any signs of sympathy for their fallen comrade Raditz when he was killed. They merely laughed and stated that he was only a "weakling", although Nappa did suggest bringing Raditz back to life with the Dragon Balls. Vegeta and Nappa themselves had a good degree of camaraderie between them, but Vegeta did not hesitate to kill Nappa later on when he displayed weakness after being crippled by Goku. Most Saiyans also possess a keen fighting sense and understanding of battle, which allows them to acquire many new skills, such as overcoming the weakness of their tails, learning to detect ki, and achieving new fighting forms and transformations.
Bardock appears to be the exception to the uncaring attitude of Saiyans: he shows some care for his wife Gine and his youngest son Kakarot (Goku) in Dragon Ball Minus, and he is shocked and saddened at seeing his crew, with his best friendTora among them, slaughtered by Dodoria in the television special Bardock - The Father of Goku. This also shows that perhaps the uncaring attitude of Saiyans is a choice, rather than natural. Bardock's last words while facing Frieza are "This is for all the people we killed in your name" (he only states this in the FUNimation dub, it is never present in the Japanese version), he also states that he was not all evil (also FUNimation dub only). After the destruction of Planet Vegeta, Bardock talks to Goku from the other side, saying "I wish I could have held you in my own two arms" (also FUNimation dub only). Even Vegeta himself later has been shown to express emotion, such as when he was dying from his wounds inflicted by Frieza, when Future Trunks was killed byCell, and when he sacrifices himself to destroy Majin Buu. Also, Vegeta's brother Tarble lacks the characteristic aggression of Saiyans, which also served as the reason why King Vegeta sent him to another planet. The existence of the original Super Saiyan God who got his power from five other pure hearted Saiyans in the past also implies that the barbaric and uncaring attitude had been a choice at some point in their history, rather than being an inborn character to all Saiyans.
The Saiyans also seem to believe that death is preferable compared to living with the shame of losing against someone inferior to them in level, which is especially evident with Vegeta and his primary motivation for his rivalry with Goku.
Saiyans naturally possess exceptional strength, far greater than that of humans and other alien races, and are quintessentially built for fighting; the average Saiyan is said to have a power of 400 to 660 by Dragon Ball Z: The Anime Adventure Game (though, in their base form, warriors can have a power level of 1,200 to 18,000). They are capable of easily lifting ten times their own weight (before receiving Master Roshi's training, Goku was already able to lift Bulma's car at the mere age of twelve). The naturally high gravity of Planet Vegeta (10x that of Earth) develops their strength, further making them incredibly strong at young ages. Even weaker Saiyans are capable of conquering most planets alone.
Through tough training, Saiyans are able to reach new levels of power, and the more intense training and fights they go through, the stronger they become. If a Saiyan survives a near-death experience through extreme injury to the body, then, when the body recuperates, the Saiyan grows much stronger than they were previously, their body adapting to compensate for the damage dealt. The duration of recovery does not seem to hinder this ability as Saiyans have healed through natural, technological and mystical means and still gained substantial increases in strength. Saiyans also appear able to heal from injuries at a faster rate than normal humans and possess a greater deal of durability to damage.
Saiyans also possess a natural affinity to the manipulation of ki energy allowing them to utilize flying and energy-based attacks with incredible ease as well as unlock great depths of power when needed, or lending energy to others in battle when it is actually necessary. Lost energy is regained by the Saiyan in a very short span of time, regardless of the amount of energy lost. Sometimes, the energy the Saiyan regained is multiplied, as noted by their power level. One of the best examples of this ability is the fights between Vegeta and Zarbon. In their first encounter, Vegeta was able to dominate Zarbon, but after Zarbon transformed, he was unable to defeat him. However, after the near-death experience, Vegeta was able to fight and kill Zarbon even in his transformed state.
Saiyans put a heavy emphasis on strength and fighting ability when it comes to importance in their society. In fact, they will excommunicate Saiyans who do not show potential to assist in their violent ways, even alleged "royalty," such as Tarble.
The Saiyans also have great speed and agility. They also have much faster reflexes than an average Human; reflexes so fast that they can avoid a bullet without much of a problem. Super speed can easily be seen in their fighting skills; their movements occur in fractions of seconds which are not visible to average Human eyes. Their agility is also substantial in their battles and training. These movements can be improved by training, transformations, and other methods. These natural powers of speed and reflex make nearly all Saiyan hand-to-hand combat very fast.
Saiyans are also noted for being ravenous trenchermen with seemingly insatiable appetites. Due to their enormous strength and intense aura, the Saiyans' energy and nutritional intake requires a great deal higher than Humans. They are often shown eating plate after plate of food, resulting in many dishes piling up (a recurring gag throughout the series), often eating more food than an average Human can muster. However, the metabolism of the Saiyans allows them to consume large quantities of food while still maintaining a muscular physique. At the end of the 21st World Martial Arts Tournament, when he was only 12 years old, Goku hastily consumed a 50 course meal (57 in the dub) in one sitting, and still had room for dessert. In Daizenshuu 4, it is stated that they have no preferences when it comes to food, although they appear to prefer meat over anything else; this is hinted with Vegeta munching on the flesh of an alien creature on the planet he and Nappa were on before departing for Earth. Note that this is not restricted only to full-blooded Saiyans, as even the normally polite Gohan has been seen eating large quantities of food.
At times, their appetite seems to work against them: in his childhood, when Goku went for too long without something to eat, he became too weak to do much of anything. It is unknown if other Saiyans, such as Vegeta, suffer from this weakness and suffered from it in their childhood. Saiyans tend to eat large quantities of food immediately before a big fight. They do not seem to suffer the cramps that Humans do by doing that; in fact, it seems to improve their overall performance.
According to the Daizenshuu, Saiyan's lifespan is about the same as an average Human (70 to 90 years, with exceptions, of course), but keep in their peak longer. Unlike Humans, Saiyans remain in their youth and prime much longer. As explained by Vegeta near the end of Dragon Ball Z, they stay young longer because they live for and are built for battle. This is seen when Nappa, who was Vegeta's attendant when Vegeta was a child, is in his prime still long after Vegeta has become an adult, but in actuality, Nappa is roughly 50 years old during his arrival on Earth. Chi-Chi complained of this in Dragon Ball GT when Goku was reduced to a child, thus making the fact that she was getting older faster that much more apparent. This is again demonstrated in the GT finale when Pan is seen one hundred years later still strong, but with gray hair despite being only a quarter Saiyan. Their natural lifespan itself is longer than humans', but since they are a warrior race, many of them die in battle, and their average lifespan is not all that long.
As far as growing is concerned, this differs by Saiyan as it does with Humans. Most full-blooded Saiyans appear to grow in spurt phases, as seen through Goku, the only full-blood ever entirely shown progressing to adult-hood. While slow growth does occur, it is just that—slow. Saiyans appear identical to that of a human baby in their early years, although they are born with a full head of hair more often than humans, and appear to grow at similar rates. At the age of 12, Goku takes the appearance of what a Human would look like at the age of 7 or 8. This is most notably showcased when Bulma clearly believes Goku to be that young, but is shocked to find out he was actually 12 years old. However, when a 5-year-old Vegeta is showcased inBardock - The Father of Goku, he looks around the same age as a 12-year-old Goku, clearly showing the difference in growth patterns of Saiyans. Goku however, even at the age of 15, has still hardly grown at all; the only differences are he has become a bit taller and more muscular, and his limbs have grown a small portion. By the age of 18, Goku had undergone his largest spurt phase. He became significantly taller, leaner, and muscular, taking the appearance of the average human at his age. As an example, the 15-year-old Goku had gone from being half the size of the 19-year-old human Yamcha, to nearly matching him in size three years later. As stated before, this differs from Saiyan to Saiyan. Vegeta, who is five years older than Goku, is shorter and smaller overall, while Raditz, Goku's older brother, is far more muscular and taller.
Saiyans appear to undergo one final growth spurt between the ages of roughly twenty to thirty, when the body seems to finalize its physical maturity. Growth in muscle mass can clearly be seen, with even some height gained. Goku and Vegeta are clear examples of this. Goku appears to have greater depth to the chest, neck, shoulders, and thighs, with other muscles increasing in size and definition after that. This can clearly be seen during the Frieza and Android Sagas: Goku appears more muscularly built than he did during the Saiyan Saga, as well as taller. Vegeta also makes a transition, appearing to even grow in height a bit, which can be seen when comparing him in the Saiyan Saga to him in the Majin Buu Saga.
It is unknown if any other drastic physical changes occur after this, as no Saiyan over the age of 60 has been clearly showcased, so it is unknown how a Saiyan above this age would change.
Saiyans have a sexual reproduction system compatible with that of normal Humans, as they are able to produce fertile offspring together. The mothers of the full-blooded Saiyans were never in the original manga, though there have been some mentions of them. When Raditz tells Goku about the destruction of their home planet in the manga/anime, he mentions that "their parents" died along with it. Their mother Gine was later revealed in Dragon Ball Minus. Also, at least in the anime, Nappa clearly states that he had a mother. Female Saiyans have been seen, including a female Saiyan holding a knife in her mouth shown in a trio of Saiyans when King Kai tells Goku about his ancestry, Bardock's comrade Fasha is a female, and a number of female Saiyans in a bar are shown in Bardock - The Father of Goku.
Saiyan families appear to be far different to that of a traditional human family; apart from the royal family of Vegeta, they are not particular about blood-relationships. Of the few (pure-blooded) Saiyan families seen, only Vegeta and his father have had close relationships, as well Broly and Paragus to some extent. Children are kept in pods as infants and monitored by doctors whilst their parents are usually occupied on mercenary missions. Even as infants, their natural strength and their Great Ape transformation means that they are capable of conquering planets like Earth single-handedly and so it is unlikely they spend much, if any time, with their parents or siblings. Notably, when Bardock is asked by his comrade Tora if he remembers what day his newborn son was born, he replies "No, but that was a long time ago." Fasha then goes on to say that it was the day before, and that he should go see him.
Saiyans do not have much of a concept of family, but they do tend to have close relationships with their friends and comrades however, with whom they do spend a great deal of time in battle. Bardock has a close relationship with his mate Gine however, which is apparently rare among Saiyans.
Due to their similar physiology, Saiyans and Humans are capable of interbreeding. While this was always possible, it became necessary for the survival of the Saiyan race when all the female Saiyans were exterminated. The resulting offspring generally possess the same enhanced strengths of the Saiyans, developing their abilities far more easily than Humans, but lack the same drive and instinct for combat. Gohan is the only Saiyan-hybrid in the manga/anime that is shown with a Saiyan tail. Hybrid Saiyans possess the potential to become Super Saiyans, but it is unclear how many generations removed from their Saiyan ancestor a hybrid can be before the transformation becomes unavailable to them. This is principally called into question because of Pan's supposed inability to transform as she is only quarter Saiyan, yet in the TV special Dragon Ball GT: A Hero's Legacy, descendants of Goku and Vegeta are able to turn Super Saiyan, despite their Saiyan heritage being even more diluted than Pan's.
It is unclear if these hybrids possess a naturally greater potential than their Saiyan parents. Gohan repeatedly demonstrated a hidden power that, when harnessed, made him more powerful than even Goku or Vegeta, and when he and Goku trained to battle Cell. Gohan not only caught up to Goku, but overtook him even before making his Super Saiyan 2 transformation; he is also noted to be the youngest Saiyan to reach that form, at the age of 11 (9 in the manga). Also, he, Trunks, and Goten were able to make the transformation to Super Saiyan at a far younger age than their fathers, with Trunks and Goten showing such ease at obtaining the first form that they treated it almost like a "child's play thing" (as stated by Vegeta in the FUNimation dub). Goten and Trunks' fusion as Gotenks shows much, much more ease in obtaining even the final form, entering the Hyperbolic Time Chamber whilst being unable to make the first transformation. In no more than about a week in the room, they emerged as a fused Super Saiyan 3.
A Hybrid Saiyan's potential may be held in check by the fact they lack the same desire for combat as pure Saiyans, and thus tend not to train as much, in times of peace, as a pure Saiyan would. For example, Gohan actually became less powerful during the seven years between his battle with Cell and the emergence of Buu, allowing Goku and Vegeta to catch up to and then surpass him, due to him having not trained enough. It is also during this time that both Goku and Vegeta make the transformation to Super Saiyan 2 as Gohan did, with Goku surpassing it to ascend to Super Saiyan 3, the last form displayed in the manga and in the Dragon Ball Z anime.
Further, it is unknown if quarter Saiyans, such as Pan, have a lesser potential than half Saiyans or pure-blooded Saiyans due to their further diluted heritage or if their comparative weakness, exhibited by Pan, is simply the result of lacking the Saiyan drive to train coupled with growing up in peaceful times. The latter would seem more likely as Bulla, Vegeta's second child, appeared to be no stronger than Pan despite her stronger Saiyan heritage.
Due to Pan and Bulla's apparent weakness, and not demonstrating the ability to transform to Super Saiyan, it is unclear if female Saiyan hybrids are weaker than male ones or if this is simply a reflection of them lacking the same instincts as pure Saiyans combined with not finding themselves in a situation likely to trigger the transformation.
As evidenced in Dragon Ball, Saiyans have a very keen sense of smell. When Goku and Krillin are looking for the rock that Roshi had thrown into the jungle, Goku is able to smell the rock which had Roshi's scent. Goku even claims his sense of smell is similar to that of a dog's (which is far superior to that of a human). This later worked against him when he met Bacterian; because Bacterian had never bathed or brushed his teeth in his life, the smell was so horrible that Goku nearly passed out. Another instance is when he is able to smell Roshi when Goku and his friends are searching for him at the 21st World Martial Arts Tournament. Goku also uses this ability to track down the thief that steals his belongings in the episode Pilaf and the Mystery Force.
Their tail also grants a Saiyan special transformations. Though a painful weak-spot for lower-class Saiyans (most upper-class Saiyans appear to have trained to eliminate the weakness), the tail allows a Saiyan to transform into a giant Great Ape beast with tremendous power when looking at a full moon. The Saiyan grows incredibly in size and tenfold in strength while drastically changing in appearance. If the tail is removed, this ability is lost. In this state, some Saiyans have limited control, but their aggressiveness is at its peak and they often become mindless animals fueled by destructive rage.
The newer form of Great Ape that appears in Dragon Ball GT, Golden Great Ape, is the far stronger transformation of the Great Ape. Their offensive capacities have become much greater, and their rage is even more intense than the Great Ape's. While in the Golden Great Ape state, the power and strength of a Saiyan increase extraordinarily. Only a few Saiyans achieved this transformation: Goku, Baby Vegeta, and Vegeta.
The most powerful ability of a Saiyan, however, is the ability to drastically augment their speed, strength and energy by transforming into a Super Saiyan. The ability is rare and difficult to achieve normally, but gives the Saiyan unbelievable enhancements to their normal abilities. Saiyans possess several Super Saiyan transformations, each different in appearance and the power they provide. For the majority of the Super Saiyan forms, the Saiyans muscle mass increases slightly, their irises turn bluish-green and their hair turns golden in color. There is a second form, and third form of Super Saiyans and even a fourth form was achieved where the Saiyans' body becomes covered in a crimson fur, the hair becomes darker and longer, and the irises alter color, (although the eye color appears to be different for each Saiyan).
In Dragon Ball Online, it is explained many Humans on Earth are now part Saiyan, giving those few the possibility of attaining the ability to transform into Super Saiyans. Female Saiyans have never been shown transformed into Super Saiyans within the anime, but female Super Saiyans appear in the computer game Dragon Ball Online and the arcade game Dragon Ball Heroes.
Saiyans have an inborn need to fight. Most Saiyans will spend their lives training to become stronger so that they can prove themselves in battle. When Frieza hired the Saiyans as his planet pirates, he knew of their amazing fighting skills and used that to his advantage. However, Frieza began to notice how powerful the Saiyans were becoming and began to fear that one day one of them would overwhelm him as the most powerful being in the universe. This eventually lead to Frieza's destruction of Planet Vegeta and all the Saiyans on it. Saiyans like Goku and Vegeta are frequently seen training and improving their fighting skills to keep up with each other's skills and the appearance of new, more powerful foes.
Many of the Saiyan and Saiyan/Human hybrids that appear throughout the series possess extreme fighting potential. It is also very common for them to develop the ability to transform into Super Saiyans at childhood, thought to be particularly likely when the hybrid's Saiyan parent had achieved the transformation prior to conception.
Like most members of the Planet Trade Organization, the Saiyan Army wears special Battle Armors to protect them in battle. This armor is shown to be extremely flexible, as it stretched so far out that it fit the Saiyan when they turn into a Great Ape. It is also light and supposedly strong, but it seems extremely flimsy in strength, as it is broken, punched, and blasted through easily throughout the series. It sometimes has large shoulder cups on the sides, although the older model does not.
Saiyans have small space-pods that are only big enough for one person. When more than one person is sent to a planet, each warrior has a pod to themselves, who fly alongside each other in a group. It is unknown what fuel the space pods use, and there is no visible exhaust area for the fuel's waste to be expelled from (though when they fly they have an energy aura around them). However, the computers operating the pods seem to be very sophisticated, and can even change course in space, despite there being no visible means of doing so (in the real world, spaceships must either slingshot around a large gravity source, such as the Moon, or must have some object to push themselves away from, per the Third Law of Motion, "For every action, there is an equal and opposite reaction"). The passenger appears to be in stasis during travel, upon reaching a destination air is pumped into the pod and revives the occupant.
In the Namek Saga, Dr. Brief was able to obtain the space pod that Goku arrived at the planet in as a baby, and was able to use reverse-engineering to builda bigger spaceship, so that Goku would have room to train in on his way to Namek. In an interview, Akira Toriyama said that the Space Pods are not so much comfortable. In Dragon Ball Minus, it is shown Bardock and a comrade flying in a bigger than usual Space Pod, enough for both to be inside of it.
After battles, injured Saiyans are placed inside Medical Machines by doctors of the Planet Trade Organization. It has high-caliber performance, being able to completely heal even a gravely injured person on the brink of death in 30 to 40 minutes' time. After a Saiyan is healed from a great injury, it has been said by Vegeta numerous times that they will become stronger. This power increase is known as Zenkai. The healed soldier can then immediately return to the battlefield.
In addition to the name "Saiyan" being an anagram of the Japanese word for vegetable, most pure-blooded Saiyans in the series also have names with vegetable puns, either in English or Japanese. Furthermore, the Saiyan Royals are keeping in line with this, simply named Vegeta(ble) and (Vege)Tarble.