The Earthlings (地球人 Chikyūjin) are the inhabitants of the planet Earth.
Dragon Ball series
They share the planet with other intelligent lifeforms, including anthropomorphic animals. They are even led by an anthropomorphic dog named King Furry. In fact, 1% of earthlings are half-breeds with some other race, 7% are monster-type, 17% are animal-type, and that 75% are the regular human-type.
The Earthlings have a large military, which has appeared throughout the series, mostly consisting of ground troops, tanks, fighter jets, and large naval ships. Earth's military usually appears when attempting to defeat many of the villains that cause massive damage to the Earth (examples being Cell and Majin Buu), but are always easily wiped out without causing any form of damage to the super villains. It could be assumed that large scale wars have taken place in the Dragon World, much like they have in the real world. However, since the Dragon World is united into a single, global monarchy, it is unknown what purpose the military serves when villains are not terrorizing the Earth that police cannot handle. It may be possible that King Piccolo's original appearance some 300 years before the events of Dragon Ball encouraged the then-king to create a military for just such purposes.
It is rare for Earthlings to have family names, with the Son family being the only known example of an Earthling family with a last name in the original version of the manga. As such, if someone were to have a title such as "Dr." it would come before their first name since they possess no last name.
Earthlings are named after a wide variety of things, though they are often named after different food or food related words.
With the exception of the uncommon hair colors and occasionally odd features (ranging from longer lifespans to werewolfism), Dragon Ball humans are identical to their real-life counterparts. Earthlings in Dragon Ball seem to be able to utilize or be affected by certain elements of magic. Akira Toriyama himself has admitted to lack of forethought or planning when it comes to the details of Dragon Ball's story, which accounts for some of the strange occurrences.
When compared to other races of Dragon Ball, average Earthlings are significantly weaker. It is said that a single Saiyan infant would be capable of destroying the average human population on its own (in fact, Goku was sent as an infant to Earth with that exact purpose). The only "normal" Earthling whose power level is reported in the manga and anime is a farmer, whose power level is 5 according to Raditz's scouter. Other "normal" Earthlings are given power levels in other media: Dragon Ball Z: The Anime Adventure Game gives Dr. Brief a power level of 12 and Bulma a power level of 16, and the movie pamphlet's for Dragon Ball Z: The Tree of Might give Good Launch a power level of 18 and Mai a power level of 20.
At the peak power a human-type Earthling can get to without possessing ki manipulation or special powers they can perform feats like destroying walls with physical blows, leaping great heights, moving fast enough to appear invisible to an ordinary human and in the anime even pulling buses and punching through metal. Prime examples of the peak a human-type Earthling can get to are Bora, Pamput, King Chappa, Nam and Mr. Satan.
Though the particularly low power levels are probably representative of normal humans, there's a fair amount of powerful "super" humans, such as Master Roshi, Tien Shinhan, Krillin, Yamcha, Chiaotzu, Mercenary Tao, Master Shen, Yajirobe, Grandpa Gohan, Olibu, Uub, General Blue, and Videl. Many of these human fighters are also Z Fighters. These few humans (minus Mr. Satan and Videl) have trained their bodies to exceed the natural limits of their race and achieve superhuman physical attributes through the learning of using ki, and are among the strongest beings in the universe. On King Kai's planet, Yamcha, Tien, and Chiaotzu simultaneously were able to trouble Piccolo and later defeat the Ginyu Force members, another showcase of an Earthling's power is that even with a small handful, they were easily capable of defeating hundreds of soldiers in the employ of the Frieza Force. However, even with such abilities, this select group of humans are still considerably weaker than some warriors of other alien races with the same ki manipulation abilities, such as Saiyans, Namekians, Frieza's race, and Majin. Their power also pales in comparison to gods such as the Kaioshin and Gods of Destruction.
As stated in the manga, it is possible for any human to use their ki and enhance their body like the Z Fighters, though according to Master Roshi, the training to achieve such thing is extremely difficult to endure for normal people, and might likely kill someone if not done correctly. For example, Gohan easily teaches Videl how to use ki to fly, however, since her physical body was not trained properly, she cannot tolerate high-speed flight and is limited in how fast she can go, since her Ki reserves are pretty short.
While Mr. Satan is considered to be the world's strongest man by humans, and has indeed showcased some degree of superhuman strength, in reality, he pales in comparison to humans like Krillin, Tien and Yamcha, who possess a lot more power. However, this is mostly due to the fact that these humans were granted more opportunities to increase their strength; for example, Krillin had his potential unlocked artificially by Guru and was trained by Master Roshi, whose training consist of increasing one's physical abilities to superhuman levels, while Yamcha and Tien trained under King Kai, whose training consists of advanced Ki control and gravity training.
Super-humanly trained warriors like Master Roshi, Krillin, Yamcha, or Tien, have immense physical strength, easily capable of breaking boulders or most metallic objects with just simple kicks and punches, the most powerful of them, are even capable of inflicting some damage to far more powerful alien foes.
While not as fast as powerful members of races like the Saiyans, Namekians etc., trained humans are able to move at tremendous speeds, with the most powerful of them being able to move faster than the speed of sound, easily able to outclass bullets, and keep up with a Saiyan's basic speed.
Trained super-humans have immensely tough bodies, capable of easily surviving bullets or even physical attacks and energy blasts from powerful Alien foes (including an attack from those who possess godly ki). Master Roshi once showcased the ability to survive a direct impact from a thunder while he was training, while the comparatively weak Bora was able to resist an massive barrage of bullets from the Red Ribbon Army soldiers that where hunting him. Despite this, super-humans can be injured by incoming projectiles if they are not focused on resisting the incoming bullet, as Krillin was once hurt while saving a fellow Police officer, although Krillin himself attributed this to being out of shape.
With enough physical power and proper ki training, humans are able to generate very powerful energy blasts, enough to easily cause big explosions, or when going full-power, even destroy the moon. A single basic energy blast from Mercenary Tao, a relatively powerful superhuman, is capable of easily killing a normal person.
However, if a person with no proper physical, or ki training attempts to do a ki-based attack, the sphere will likely dissipate within seconds, just like Videl, who can indeed produce energy blasts, but with no control in directions or enough power to actually cause significant damage to her opponents.
Reproduction with other Species
However, while these offsprings possess immense power, and, in the case of Gohan, have near-unlimited potential, they lack some of the natural pure-blood Saiyan traits, such as the Saiyan's natural never-growing black hair. However, their ki control is still far more advanced and powerful than that of normal Human beings, and are just as physically powerful as any other Saiyan. They also possess the Saiyan Power to grow stronger after healing from near fatal injuries.
In Dragon Ball Super, it is stated that the Earthlings from Universe 6 were wiped out a long time ago due to a war breaking out. After learning that the Earthlings made incredible delicacies, Champa decides to challenge Beerus in order to take over Universe 7's Earth in a Universe 6 and Universe 7 tournament consisting of five on five combat, using warriors from their own universes.
After the tournament, the Earthlings of Universe 6 were brought back from extinction through a wish from the Super Dragon Balls.
Dragon Ball Online
It is explained in Dragon Ball Online that, after Gohan writes the book Groundbreaking Science in Age 804 that unveils the secrets of ki control (Spiritualist) and advanced martial arts (Martial Artist), fighting becomes incredibly popular amongst the Humans, thus ushering a new age of Human warriors after the Z Fighters' end.
One section of Gohan's book explains that the dense material Katchin could be 'cut'; what this means is unknown; if Gohan meant that it could be turned in weapons like swords or if it could be sliced through with a powerful enough strike, as he failed to do years earlier with the Z Sword. Nevertheless, this intrigued Trunks and Goten. Meanwhile, after reading "Groundbreaking Science", some humans became intrigued with the idea of channeling their ki energy into swords to increase striking speed and power. To instruct the newer generation of heroes, Trunks and Goten create the Kikoukenjutsu Sword School. In Age 820, remnants of Frieza's Frieza Force attacked Earth, and were fended off by with much help from the Kikoukenjutsu Sword School.
Meanwhile, Master Roshi wishes to return to teaching, but felt that he was too old to possibly instruct fighting. In order to succeed his teacher, Krillin created the New Turtle School that emphasized on team work. While Krillin had fought many major battles alongside the Z Fighters, in his experience, he learned that team work was the most effective. But after learning of Kid Buu's defeat by Goku's Super Spirit Bomb, Tien's belief was that even the greatest enemy could be completely destroyed with a strong enough ki attack. His New Crane School would emphasize on producing powerful ki attacks at the cost of health, rather than actual energy itself. The revival of these schools greatly aide the Humans in their conjoined efforts to stop the game's central villain, Miira, who seeks to obtain the DNA of Earth's greatest hero: Goku.
As of Age 1000, the human race has become cross-bred with the Saiyan race via Goku and Vegeta's descendants. Many believe that the race holds a powerful, hidden potential due to their part Saiyan blood. As such, in-game, the Super Saiyan transformation is granted to them by Shenron.
Dragon Ball: Xenoverse
Human (referred to as Earthling) is one of the Future Warrior's selectable races in Dragon Ball: Xenoverse. In this game, Human's have fairly balanced stats, offering the well-rounded option for players who don't necessary favor offense over defense or vice-versa. Their Ki refills automatically, with their attack power increasing when their Ki is at maximum. Unlike Dragon Ball Online they are unable to use the Super Saiyan transformations, however they can use Kaio-ken, Kaio-ken x3, and Kaio-ken x20. By training under Old Kai as they can also undergo his ritual to access their Unlocked Potential.
The balanced stats of the Human race, plus the automatic Ki regeneration ability makes them much easier to learn and use than other race.
In the Parallel Quests, if the selected Future Warrior's race is Earthling, other Human characters (like Yamcha and Krillin) will acknowledge them as an equal and will fight with all they got, whereas non-human characters (like Vegeta, Frieza and Cell) will underestimate them. Interestingly, a human Future Warrior can reach incredibly high levels of power to the point they are able to fight against the likes of Beerus, Demigra, Broly, Golden Frieza, Great Ape Baby, Super 17, and even the Shadow Dragons.
On the flip side, several mentors will make note of their abnormal strength that far surpasses regular Earthling standards. Cell himself will state that if he absorbed them, then he could've reached his perfect form faster.
Dragon Ball: Xenoverse 2
Earthling is once again, one of the 5 selectable races. Like the prequel, they have balanced stats, automatic Ki recovery and their attack power increases when their Ki is maxed out.
At the beginning at the game, the Earthling will be at Satan House before Old Kai tells them to make their way to Conton City. If an Earthling Future Warrior visits and accepts Hercule's request at the latter's mansion, they can obtain extra Zeni when they complete his missions.
An Earthling Future Warrior has a unique transformation of their own called Power Pole Pro, where they summon the Flying Nimbus and wield the Power Pole. The Power Pole Pro Awoken Skill can be obtained by reaching Level 35 and joining the Saiya Squad inside the Satan House time rift anomaly. This will cause Great Saiyaman 1 & 2 to suggest they come up with something unique to help them stand out. The Warrior must then speak to both Jaco and Mr. Satan. Jaco will suggest they find some kind of weapon and Mr. Satan will suggest a cool vehicle. The warrior must then return to Great Saiyaman 1 & 2 to tell them what they have come up with leading to Satan House Quest: "Earthling Awakening" where they face off against Great Saiyaman 1 & Great Saiyaman 2, unlocking the skill mid-battle. They must then defeat Great Saiyaman 1 & 2 after they revive to complete the mission and unlock the skill permanently.
Like in the previous game, their abnormal power level are noted to rival that of Saiyans and the other 3 races.
Some alien instructors will become shocked that an Earthling could reach that level of power. Also if the Future Warrior wears Krillin's Battle Armor while talking to Frieza, after recognizing it as the armor Krillin wore when Frieza killed him, Frieza will ask the Future Warrior if Earthlings are a noseless species (a reference to Krillin's lack of a nose) out of curiosity.
Power Pole Pro
Main article: Max Power
A powerful transformed state usable by Human-type Earthlings, however it is only ever displayed by the Turtle Hermit Roshi. In this form, a human's appearance changes dramatically, gaining a massive increase in strength and muscle mass.
A permanent enhancement which turns the Human part android, several different types of human turned cyborg have been shown, such as Mercenary Tao, Lapis (Android 17), Lazuli (Android 18), Dr. Wheelo, and Dr. Gero (Android 20).
Four types of technologically enhanced Humans appear, the first is Cyborg Tao - who gained crude cybernetic parts to his body, the second is Wheelo - who simply implanted his brain into a mech suit, the third is Android 20 - who possess a half human-half robot body, and the fourth are Androids 17 and 18 - who possess little to no cybernetic parts and are instead Humans with reconstructed organic matter.
Depending on the technology used to modify and enhance them, some Androids like 17, 18, and 20 lack ki signatures, while others such as Mercenary Tao and Dr. Wheelo are still detectable. The power possessed by these modified humans also varies depending on the technology used to modify them. For example, the more crude cyborgs - Cyborg Tao and Wheelo - were completely outclassed by the later more advanced cyborgs such as 17, 18, and 20.
Dragon Ball Heroes avatar
Using the advanced time manipulating properties of the Dragon Ball Heroes machines, Humans are able to take on the form of a member of one of the following: Saiyan (and several of their forms), Namekian, Majin, Frieza Clan, Android (and Bio-Android), or Supreme Kai. They can further power up using Class-up, Super Class-up, and God Class-up.