A Sky Bison, also knowing as a 'Flying Bison' is an species of animal that was native to the Air Temples living along with the Air Nomads. At one stage, these animals were close to extinction. Avatar Aang believed that his Sky Bison, Appa, was the only one left from existence until they found a herd after the Hundred year war. Many sky bison are located at the Air Temple Island which is near the Republic City.
The Sky Bison were the first ever airbenders and they inspired air bending. Similar to how the dragons inspired firebending, the moon inspired waterbending and the Badgermoles inspired earthbending. These creatures are well respected by the Air Nomads. Airbenders have an arrow mark on their body which was another inspiration from the Sky Bison as they have an arrow mark on their head.
Sky Bison are well known for companionship, it is said that once someone chooses their Sky Bison they will remain good friends for a very long time. They are used for a way of transportation, they used to to be the only way of transport to the Air Temples.
 Notable sky bison
Appa the sky bison, is Avatar Aang's animal guide and was one of the main animal characters in the series, the other being Momo. Oogi has often been seen in the the legend of Korra who is owned by Tenzin and his family.