Kuruk

"water"

- Aang, you must actively shape your own destiny, and the destiny of the World.

Avatar Kuruk was a previous incarnation of the Avatar. He was the last Avatar from the Water Tribe, prior to the birth of Korra. He was succeeded by Kyoshi, and died 400 years before the events of the series. Kuruk was a gifted, cocky Avatar who professed to having a "Go with the flow" attitude to his position. This attitude had major consequences for Kuruk, who lost his wife to the spirit Koh because of it.

Kuruk was first seen in "The Avatar State". However, only a glimpse of him doing an incredible waterbending technique is seen. His name and actual history are revealed in the online game, Escape from the Spirit World. He was first mentioned in "The Siege of the North, Part 2" as the Avatar who tried to kill Koh, though at that time his name and origin were not mentioned.

History
Kuruk was a gifted, but cocky Avatar who enjoyed constantly searching for people to challenge them to contests of bending powers, usually for no other reason than for the fun of it. He also liked showing off grand displays of his bending ability to others, especially beautiful women. He has been shown Airbending lotus tornadoes for Air Nomad ladies, challenging random Fire Nation people to an Agni Kai, and engaging in earth-lifting contests with Earthbenders.

Kuruk was a 'go with the flow' kind of Avatar. During his time the world was generally at peace with no wars or disputes at all due to the efforts of Avatar Yangchen, the Avatar before him. This allowed him to step back from his responsibilities as the Avatar and let the Four Nations resolve their own differences. Although there was peace, Kuruk's carefree lifestyle would eventually cost him dearly.

Never having even the slightest thoughts of settling down, Kuruk went on with this up until the day he met the love of his life. At the New Moon Celebration, a meeting of the two Water Tribes, he met a woman named Ummi from the Southern Water Tribe, and it was love at first sight. Shortly after, Kuruk presented her with a customary betrothal necklace, which she accepted, and the two were to be married at the Spirit Oasis.

On the night of their wedding, as they approached the altar, Ummi fell into the pond, seemingly pulled in by an unseen force. As it turns out, she had been taken by the spirit Koh, the Face Stealer, to punish Kuruk for his past arrogance. Ever since that day, on the anniversary of their wedding, Kuruk traveled to the Spirit World in hopes of saving Ummi, but failed on every attempt. His attempts are what has given Koh his grudge against the Avatar. Now in the Spirit World, Avatar Kuruk still searches for his wife, with information on her present state imparted to him by a brief encounter with Aang enticing him even further.

Appearance in Aang's Life
Aang called Kuruk forth to ask how he could defeat Fire Lord Ozai without killing him. Kuruk told Aang to actively shape both his destiny and the destiny of the world, as it was Kuruk's own arrogance and inaction that cost him his beloved wife (he clearly has yet to succeed in saving Ummi). Aang takes this to mean that Kuruk, like the other Avatars, said it was necessary to use lethal force in order to protect the world. However, Kuruk's answer is much more open to interpretation since "actively shaping your destiny" could have various meanings. He was later succeeded by Avatar Kyoshi.

Trivia

 * Kuruk's voice actor, Jim Meskimen, also voiced Lieutenant Jee and General How.
 * Kuruk has a physical resemblance to Hakoda.
 * Kuruk's name is a palindrome.
 * It can be assumed that Kuruk chose to master Airbending at the Eastern Air Temple, not only because all of the Airbenders there were women (which would certainly be a large part in his choice), but also because the temple seems to be scattered on several small mountains.
 * Also, in his Airbending training, Avatar Kuruk is seen with a customized Air Nomad uniform that is similar to Aang's, but in varying shades of blue.
 * Kuruk is the Pawnee Native American word for "bear". This could be a reference to the Water Tribe's cultural similarities to the Inuit people. His name may also be related to the bearskin pelt he is frequently seen wearing.