He is an especially gloomy mule who wanders aimlessly, pondering sad facts and possibilities.
Eeyore's character is very pessimistic, having never been exposed to the harsher realities of life outside of his world in the 100 Acre Wood. Because of this, he often thinks things on the bad side, but is always willing to help his friends.
Eeyore is a rotund, grey donkey with a light grey underside and mouth. He has long, floppy ears and a long face. His eyes are black and always half-shut, and his eyebrows are black. He also has a thick, black "crest" of hair lining the top of his head to roughly halfway down his back. The middle of Eeyore's face sports a seam, and he has a grey tail that is attached to his rear by a tack (possibly a reference to pin the tail on the donkey), which he often loses. His tail sports a black tuft of fur on the tip and a pink bow tied on it just below this.
Eeyore was not present until Sora collects the missing pages of Pooh's storybook. When Sora, Pooh, Piglet, Owl, Tigger, and Rabbit visit a river, they find Eeyore floating down the river. Sora rescues him and then helps him find his lost detachable tail.
Like all of the other Winnie the Pooh characters, he is part of the mini-game "world" of 100 Acre Wood, where he is found while leading Pooh from one end of the map to the other.
When the Heartless tore out the pages of the book again, most characters in 100 Acre Wood disappeared, leaving only Pooh within the world with no memories of any of his friends. To solve this problem, Sora went on another journey to find the scattered pages of the book and assisted Pooh's friends in helping Pooh regain his memories of them. When Eeyore finally reappears, Pooh doesn't remember him until after Sora and Rabbit give Pooh honey in an attempt to use food to trigger his memory.
Eeyore's character is based on a real life stuffed animal owned by A. A. Milne's son, Christopher Robin Milne.