Saiyan

Ancient Eurasian-based humanoids, they are the space nomads Goku and the majority of other main characters are answered to be. They are complete opposites in the 2 universes: Peaceseekers in 6; Violent in 7.

Toriyama's Creation
The name is a pun on yajin (野人) which means "wildman", and an anagram of yasai (野菜) which means "vegetable". The suffix -jin means "person". "Saiyan" is the English transliteration of the roman letter term Saiya-jin. In the Japanese language, Saiya-jin (サイヤ) is pronounced "Sigh-ya-jeen" while in the English dubs, "Saiyan" is pronounced "Sey-uhn".

All full-blooded Saiyans (such as Raditz, Kakarot, Vegeta, Nappa, Paragus, Broly, or Bardock) have names that are a pun on various vegetables.

Physiology
Saiyans are commonly seen to have black spiky hair and black eyes (although the anime has occasionally shown brown, blue and blonde hair and purple eyes). Naturally growing stronger as they mature, they gain a very muscular and well-defined build.

Vegeta states that the hair of a pure-blooded Saiyan does not deviate from its appearance from the day the Saiyan is born. However, it can fall off, as seen with the bald Nappa (he had hair in the TV special Dragon Ball Z: Bardock - The Father of Goku). This is somewhat contradicted by a young Vegeta shown with strands of hair hanging in front of his forehead, but later has his characteristic widow's peak. This is not the case with hybrid-Saiyans who are shown to have several different lengths and styles for their hair throughout the series.

Facial hair of pure-blooded Saiyan males can grow. Some examples are Nappa, Vegeta, and Paragus who have all been seen with mustaches, while King Vegeta himself had a beard. While Saiyans can grow beards it apparently takes them a long time, as seen when Goku and Vegeta spent three years in the Hyperbolic Time Chamber, yet only grew enough facial hair to cover their faces. Given that Saiyans have evolved to have a slowed aging process upon reaching physical maturity in order to fight longer, this is most likely why it takes so long for Saiyans to develop facial hair.

Saiyans usually have dark eyes, though half-breeds do not always share this trait as Vegeta's son, Trunks, and daughter, Bulla, inherited blue irises.

Saiyans, at least as adults, are resistant to extreme temperatures, far more so than humans, as evidenced by Bardock going into outer space to face Frieza for the last time, Broly surviving being frozen in a glacier, and Goku training in the Hyperbolic Time Chamber and facing Lord Slug and his minions when they used a machine to cause the Earth's climate to get extremely cold. This resistance to cold is likely either a trait gained over time from evolution in harsh climates or due to the energy consumption of Saiyans increasing their ambient body temperature far above a human's, even in a resting state. Even in a functional, calm state, Goku has shown to be unaffected by glacial temperatures on Earth.

Tail
All pure-blooded Saiyans from Universe 7 are born with a brown-furred monkey-like tail. Commonly for adult Saiyans, they will wrap their tail around their hip as a makeshift belt for better convenience. The tail is very prehensile, and can be used to grasp things (much like some new world monkeys do), giving them in a sense an extra hand to fight with.

While as strong and coordinated as any other limb on the Saiyan, the tail is a particularly sensitive area. When grabbed or injured, it causes great pain to the owner, leaving them drained of all strength and effectively immobilizing the whole body. However, the Saiyans can train themselves to overcome this weakness, leaving them unaffected altogether, like Goku did when he preparing for the 22nd World Martial Arts Tournament or Vegeta and Nappa before coming to Earth. Their monkey-like tails, alongside their turning into Great Apes, is the main reason why those of Saiyan descent are sometimes referred to as "monkeys" or "apes" as a racial slur (especially notable by the Frieza Force's reference to them as such).

The tail also serves to help young Saiyans with balance, as when Goku and Gohan's tails were first removed, they had trouble standing, let alone moving about. However, when Vegeta's tail was cut off, his balance was unaffected, possibly due to the Saiyan prince having adjusted to the balance after years of wearing his tail at the hip.

As noted by Raditz, the tail is the source of a Saiyan's true strength (Great Ape form), enabling them to perform to their maximum efficiency. This was supported by Goku who once stated that he feels stronger with it than without it. The most unique and prominent ability the tail provides Saiyans is to transform into a Great Ape if exposed to the Blutz Waves of a full moon. If the tail is removed, this power is lost, forcing them back into their normal state if transformed at the time. If the tail is lost it will often suddenly grow back if the Saiyan is in danger. However once a Saiyan reaches a certain level of strength the Saiyan's body seems to deem the tail as an unnecessary appendage if removed. A Saiyan's tail has an 8% chance of growing back, and will not grow back if they have surpassed the power of their Great Ape form in their base form.

It is shown in Dragon Ball GT that the tails also provide a boost in Super Saiyan transformations, as when Goku was shrunk into the size of a child, he had trouble maintaining his transformations until his tail reformed, to the point where he was able to easily activate Super Saiyan 3 and maintain it for a considerable amount of time (along with his tail's fur turning gold).

Gohan is the only half-breed Saiyan seen with a tail in the series. Other half-breeds like Trunks, Goten, and Bulla are not seen with tails. The reason behind this is never explained in the series other than it was hypothesized their tails were removed at birth, but Akira Toriyama has stated that tails are a recessive trait. Despite most deceased warriors who keep possession of their bodies are healed from any injuries or dismemberments (i.e. Tien Shinhan's severed arm), no Saiyan with a lost tail are shown to have regrown it upon being resurrected.

In Universe 6, Saiyans naturally no longer have tails. This is because of the evolution process they underwent in their universe, presumably enabling them to naturally access maximum capacity without additional training. It is unknown if this permanently voids Universe 6 Saiyans of the Great Ape form or can access it without the need of a tail.

In the Super History Book, released on January 21, 2016 as part of the celebration of the 30th anniversary of the Dragon Ball franchise, Toriyama finally explains the reason why he did away with Saiyans' tails. He explains that it was confusing for him how Saiyans dressed themselves with the tail on, and these sorts of minutiae annoyed him to no end, enticing him to get rid of Saiyans' tails.

Universe 6

 * Evolved Saiyans

The Saiyans of Universe 6 differ from their Universe 7 counterparts in that they never left Planet Sadala and are a more heroic species. Additionally, they have evolved so they no longer possess tails and subsequently can't access the Great Ape form through conventional means. They have displayed the ability to achieve the Super Saiyan form, as well as Super Saiyan 2.


 * Tuffle hybrids

Tuffle-Saiyans only existed in Age 780 as a result of Oren and Kamin invading Sadala. Fully Tuffleized Saiyans have displayed their own variants of the golden-haired Super Saiyan forms known as the "Strongest Forms".

Legendary
Legendary Saiyans are a unique type of Saiyan that exist in both Universe 7 and Universe 6. An individual Legendary Saiyan is born once every 1,000 years in both universes. These Saiyans are demonic mutants and have massive power levels even upon birth. While not shown to be able to take on any normal Saiyan forms aside from the basic Great Ape, these Saiyans possess their own transformation line based around the Legendary Super Saiyan state.

Despite their demonic nature, Legendary Saiyans can be gentle hearted as shown by Kale of Universe 6 and Broly of Universe 7. However because of their demonic nature they can end up becoming violent, blood thirsty, and destructive like the original Broly, his clone Bio-Broly, and alternate world counterpart Dark Broly. Because of their destructive tendencies legendary Saiyans are feared in both Universe 6 and 7, though in Universe 7 they are often associated with the legends pertaining to the Super Saiyan of Legend as the general Saiyan population in Universe 7 tends to be more barbaric and violent than their more evolved Universe 6 counterparts.

Universe 7

 * Ancient Saiyans

Ancient Saiyans (alternatively known as Prehistoric Saiyans) existed long ago. Aside from time travelers, none still exist in the modern time. They possess ki completely different from their modern day counterparts and like them can transform into the Great Ape, Super Saiyan, Super Saiyan 2 and Super Saiyan 3 forms.

The first type of ancient Saiyan was the evil type, the most notable being Cumber, who displayed the unique "Evil Aura" and as an extension of this, their golden-haired Super Saiyan forms possessed differences to modern Saiyans and they were capable of drawing out the full power of Super Saiyan 3.

The second type of ancient Saiyans was the good type: the "Super Saiyan God race", these most notable of these ancient Saiyans was the previous Super Saiyan: Yamoshi. Good ancient Saiyans are referred to as "the defeated" by Giblet due to them having been defeated and killed by evil Saiyans. They possess the potential to become Super Saiyan Gods.


 * Modern Saiyans

The modern Saiyans are descended from the evil ancient Saiyans who killed Yamoshi. The Saiyans who eventually joined the Frieza Force were the Saiyans who moved from Planet Sadala to Planet Vegeta, nearly all of them were wiped out by Frieza - leaving only a handful remaining. These Saiyans have displayed the ability to take on any Saiyan form aside from the full power Super Saiyan 3 and those exclusive to the Legendary Saiyan. Modern Saiyans are referred to as "the tainted" by the Giblet due to possessing the blood of the evil Saiyans.


 * Earthling hybrids

While the Saiyans who worked under the Frieza Force are near extinct, they have carried on through Saiyan-Earthling hybrids through Goku and Vegeta, with these hybrids being fairly common by Age 1000.


 * Bio-Androids

Through advanced science, hybrid clones composed of Saiyans along with numerous other races were created from Age 767 on-wards. Bio-Androids like Cell have displayed the ability to use the Super Saiyan forms. The demonic Saiyan Bio-Androids have displayed their own distinct Super Saiyan form.


 * Godly beings

Saiyans who are full deities can also exist, though only one ever has as a Supreme Kai candidate. Saiyans who are proper godly beings possess natural god ki, as well as an altered Super Saiyan Blue.


 * Tuffle hybrids

Tuffle-Saiyans only existed in Age 789 as a result of Baby and his Tuffle Parasites invading Earth. Fully Tuffleized Saiyans have displayed their own variants of the golden-haired Super Saiyan forms known as the "Strongest Forms".