Body markings are widely used throughout the World of Avatar, and are applied for a variety of purposes. Some, such as makeup and other cosmetics, are used for statements of beauty or fashion and are not unique to any one group. Other markings serve purposes of identification—usually with a specific group or nation—and carry a deeper level of cultural symbolism.
Airbending master tattoos
Upon reaching the level of master, airbenders are tattooed with five light blue arrows: one extending from the base of the spine to the forehead, one for each arm pointing to the hands, and likewise for the legs and feet. This pattern is an emulation of the flying bison's natural markings, as they were the first airbenders. Unlike most master airbenders who gain their status later in life, Avatar Aang received his tattoos when he was only twelve, following his invention of the air scooter. This made him the youngest known airbending master until his granddaughter Jinora received her tattoos at the age of eleven in 171 AG.
As they run along chi paths, the tattoos of an Air Nomad Avatar will glow when they enter the Avatar State. If the Avatar's body has received a severe injury on a tattooed area, leaving a scar deeper than the tattoo, then that particular spot will not glow.
The earliest known ancestors of the Air Nomads lived on top of the air lion turtle during the era of Raava and had similar tattoos along their bodies, though the ends bore an upside down "T" with a dot beneath it and they were applied even to children. As these people only received the power to control air while out of the city, the tattoo was not associated with airbending mastery.
Mark of the Brave
The Mark of the Brave is a crescent-shaped mark that resembles the moon and is given for "inspirational displays of courage." During Sokka's rite of passage, Katara held the position of bravery as she needed to secure the boat's mainsail and thus prevail against the brutal winds. Following her successful completion of the ritual, Bato bestowed the Mark of the Brave upon her.
Mark of the Trusted
The Mark of the Trusted is a horizontal arc given to outsiders who are able to prove themselves worthy of the Water Tribe's trust. For example, while ice dodging, Aang controlled the jib of his group's cutter to successfully navigate the rocky waters; this position related to trust, as without a steady hand, the whole crew would go down.
Mark of the Wise
The Mark of the Wise is a horizontal arc above a dot and is given for deft decision-making and the ability to maintain leadership under pressure. Hakoda received this mark, and years later, so did his son, Sokka, for steering the boat as well as for leading Aang and Katara wisely through the rough waters by instructing them on what to do.
Water Tribe Warriors, elite nonbending fighters of both the Northern and Southern Water Tribes, wear full-face war paint when going into battle, colored black, gray, and white. In the Northern Water Tribe, it is also customary for the chief to ceremonially apply three red markings to the forehead of chosen warriors departing on a dangerous mission.
Earth Rumble VI
During Earth Rumble VI, certain fighters were tattooed or wore body paint or make-up: The Boulder possessed a tattoo of a badgermole on his back, a self-proclamation of his earthbending prowess, and Headhunter's face was painted as part of his fighting persona.
The all-female Kyoshi Warriors have a strict garb which is worn both in battle and during training. A key feature of this uniform is facial paint, consisting of a white foundation with accents in red and black, meant strike fear into the hearts of the warriors' opponents. Along with the armor and weapons of the uniform, this paint was designed to resemble the attire of Avatar Kyoshi.
All members of the Sun Warriors, an ancient firebending civilization predating the modern-day Fire Nation, bore two red markings on their cheeks, foreheads, noses, and various other spots on their faces, which they kept on throughout several different occasions. The sole known exception to this is the Sun Warrior chief, who only wore red war paint from below the eye area, up into his face, which was bordered by a level of white face paint.
Combustionbenders, firebenders with the rare ability to shoot an explosive beam of energy from their forehead, have a tattoo of an eye on the spot from where their attack is released. Although this tattoo marks the bender's point of power, it also marks their weak spot; by striking this spot or continuously blocking it, the bender's flow of chi can be interrupted, preventing them from using their abilities.
Although the main feature of this tattoo is a red eye positioned vertically, other features of the design can vary; while Combustion Man and P'Li both had three pinkish, horizontal lines surrounding their third eye, his were thick and straight, while hers were more refined and curvilinear.
The elite marksmen of the Yuyan Archers bear dark red tattoos that run as a strip across their eyes, the ends of which flare out over the forehead and cheeks while the center narrows over the bridge of the nose. The placement of their tattoos symbolizes the importance of sight in their deadly skill. Similar in principle to the tattoos of master airbenders, the tattoos of the Yuyan Archers identify them as part of an elite group.
Official Avatar Aang Fan Club
In the Yu Dao chapter of the Official Avatar Aang Fan Club, the girls took mastering a kind of faux airbending very seriously and even began tattooing themselves in a way similar to master airbenders. However, Avatar Aang saw the tattoos as disgracing his culture, so as he began to teach the club members about his culture and renamed the fan club the "Air Acolytes", the practice of tattooing was discontinued.
Other groups and individuals throughout the four nations also bear tattoos, which do not generally seem to have any significant meaning. The bounty hunter June, for instance, had a red tattoo depicting a coiled snake on her shoulders. Tattoos are common among criminals, or people who participate in otherwise less than legal activities. These can be evidenced by the pirates pirates that attacked Aang and later Zuko, and also the criminals imprisoned in Chin village. One prisoner in Chin Village noted that tattoos would help one fit in among other criminals. In addition to the criminals from Chin Village, tattoos were common among prisoners in the Boiling Rock as well.