That is the beauty, you can create anything you want!
If you want a magic rabbit species that can take the form of humans, you can create it. A fantasy novel is limited only by your imagination.
However if you are interested in a few already in existence then consider the following:
Werewolves. Humans who change into wolves either when they are angry or in the light of the full moon. This can be taken to include almost any animal. Werecats, Werebunnies, Werewombats. You name it.
Vampires. These are the cliche immortal human race. Never age, brimming with inhuman strength and speed. In some myths they can change into bats, or wolves, or mist, and have other abilities. (I would however steer clear of the mayervamps and their sparklyness).
Dragons. It is common dragonlore (at least in the D&D world) that powerful dragons can take human form. Another version of this is a little known book called the Dragon DelaSangre (spanish meaning of the blood). It is about a family of dragons that can take human form.
Immortals. No need for a mythical species, just create a race of humans that are long-lived or immortal. Like Highlander. But put your own spin on it.
Again, I stress the fact that the good thing about fantasy is the ability to do whatever you want. To make whatever you want.
