Hares were members of the Old Narnians. They were called into existence at the birth of Narnia, and were most likely part of its first council.
No doubt the Hares, like most Narnian creatures, were similar in appearance to Hares on earth, but were a great deal bigger.
Hares were present at the meeting at the Dancing Lawn, and one notable hare was Camillo who smelt Doctor Cornelius at the meeting.
Another notable Hare was Moonwood, who lived during the Age of Conquest.