Topic says all. Has to be a real animal. Extinct ones are okay.
Mine change once or twice a year, but it always cycles between the same five animals:
Wolves (particularly the Grey wolf and the Timber Wolf)
Panthers (Black ones)
Foxes (preferably red ones, but artic foxes are great, too)
House Cats (love them all the same)
Giant Pandas (as in the species not larger-than-life pandas)
Honorable mention goes out to dogs, but they always end up being runner-ups for some reason.
As you can guess, this is the year of the wolf for me. Maybe this time they'll stay a little longer as my favorites, now that I'm trying to develop a wolf character.