Horace Horsecollar appears in Kingdom Hearts II, residing in Timeless River. In Kingdom Hearts Birth by Sleep, his only other appearance, he is shown to reside in Disney Town. In Kingdom Hearts II, he does not play any essential role other than walking around the Cornerstone Hill with Clarabelle Cow and Clara Cluck. His role is greatly expanded in Kingdom Hearts Birth by Sleep, however, as he interacts with Terra, Aqua, and Ventus. It is assumed that he is still present in either Disney Town or Disney Castle during Kingdom Hearts II, but Sora never encounters him. In addition to his minor appearance in Kingdom Hearts II, one of the bonsai figures in the Courtyard of the Disney Castle bears a striking resemblance to Horace Horsecollar, in a percussionist's guise. It could very well be him, as he was the percussionist in The Band Concert.
 Kingdom Hearts Birth by Sleep
Horace comes yelling for help after the Unversed infest the "Fruit Ball" Area, but Pete runs away and Aqua volunteers to help. After Aqua defeats the Unversed, Horace introduces her to The Queen. Horace then votes for Aqua as his hero. He is present to witness the announcement of the Million Dreams Award and Pete's banishment.
During the ending credits, he watches Huey, Louie, and Dewey race on the rumble racing grounds.
 Kingdom Hearts II
Horace appears in the past, Timeless River. He appears along with Clara Cluck and Clarabelle Cow.
Horace Horsecollar is an anthropomorphised horse. In Kingdom Hearts II's Timeless River, he takes on a retro, monochromatic look, with completely black fur, rubber hose limbs, and a short, black tail. His hooves are white and a strange, semi-circle shape, and he wears the famous white gloves common to many older Disney characters on his four-fingered hands. He has large, close-set eyes and a white mouth with straight, white teeth. His ears are also rather long and floppy. He wears a small, white hat with a black band around the base strapped to his head by a white chinstrap. His namesake, his horse collar, is a round, white ring with a black bow on its front and a black prong tipped with a white ball on the opposite side. It hangs loosely around his neck.
In Kingdom Hearts Birth by Sleep, Horace is seen in full color, with a slightly modified design. While his fur is still black and he retains his white gloves, his hooves are now a slightly different shape and he seems to be wearing tan shoes over them. He wears blue overalls and a red, long-sleeved shirt, and his hat is now brown with a blue band. His mouth is light tan and his ears are no longer floppy, and instead point upward. His horse collar is now completely brown with a red bow.
Horace first appeared in The Plowboy, simply as Mickey's plough horse. After milking a cow, Mickey gives Minnie the milk. After that, Horace is stung by a bee and goes on a rampage of pain breaking the plough. Mickey replaces Horace with a pig in the end.