Yax is a yak, and the owner of a local club in Sahara Square, known as the Mystic Springs Oasis. Yax, like the club itself, is very unique in the city of Zootopia, being that he is a naturist (or naturalist as he calls it). Despite the fact that animals have evolved to the point where wearing clothing is commonplace, and doing otherwise is looked down upon, Yax and his acquaintances within the club believe that the idea of animals wearing clothes is odd, and use the Mystic Springs Oasis as a way to voice those opinions, while being allowed to act as themselves and bond amongst one another.
Yax is usually found at the front desk, being the first animal greeted in the club. When not interacting with employees and guests, he can be seen meditating—rather loudly.
Yax the Yak is the most enlightened, laid-back bovine in Zootopia. When Judy Hopps is on a case, Yax is full of revealing insights.
Yax is a free-spirit. He cares nothing for the negative opinions towards himself or his beliefs; so much so, that he appears oblivious to those who are uncomfortable towards his naturalistic lifestyle. As such, he is welcoming to all who enter his establishment, nudist or not, and can be very social and inviting as a result. Being a spokesperson of sorts for animal nudists, Yax appears to act as an inspiration amongst his peers, with his philosophical nature serving as a heavy influence.
Yax's level of intelligence is debatable. On the one hand, as mentioned above, he is very oblivious and slow-witted at times, while on the other, he has an impressive memory, and also shows to have some knowledge about the inner-workings of vehicles.
Yax is a brown, rather unkempt yax. He has a massive bush full of hair, with various flies swarming about. Unlike real yaks, Yax is relatively scrawny, albeit with a potbelly. He wears a bead necklace and bracelets, while his hair is covered with orange flowers. Other than that, he wears no clothes of any kind whatsoever.
Yax is first seen meditating at the front desk of the Mystic Springs Oasis, where he is visited by Judy Hopps and Nick Wilde, who are searching for the missing Emmitt Otterton, a frequent guest of the club. Yax initially turns Judy away, believing her to be a scout selling cookies, but he complies to assist the duo upon recognizing their mission, as well as Otterton.
He takes both Nick and Judy through the pleasure pool to seek Otterton's yoga instructor and unknowingly makes Judy highly uncomfortable, due to the nudity of both himself and his guests. While touring through the area, Yax explains his ideals to the duo, and upon greeting Nangi, Otterton's instructor, it appears she has no memory of Otterton. Yax tries to jog her memory by spewing various details about Otterton during his last visit, including when he last visited, the car he was seen entering, and the license plate of said car. Yax's limited intelligence kept him from realizing that he was more than enough help for Judy, though the former gives credit to Nangi for providing helpful assistance.
During the end credits, Yax can be seen attending and dancing at Gazelle's concert.
An emoticon version of Yax briefly appeared in the Zootopia entry of the As Told by Emoji short series.
Due to his refusal to wear clothing, despite living in a world where animals normally wear clothing, Yax can be classified as a nudist.
The correct term for Yax's club should be "naturist" and not "naturalist". It is unknown if this is a mistake on the filmmakers' part, a sign of Yax's slow-witted nature or in the movie's world, the word has a different meaning.
Since there are no birds or reptiles seen in Zootopia as the movie has an all-mammal cast, the flies buzzing around Yax's head are the only non-mammalian animals seen in the entire film.