You might find this helpful: List of all Wings, Cosmetics, Pets, and Promos
There’s 19 pets from pet goblins, 11 from seasons, 2 from RoS/Necro DLC, 2 from the Darkening of Tristram event, one from a unique mob (Liv Moore from Ravi Lilywhite). Then there’s some more from Blizzcon as well as from cross-promotions with other Blizzard games.