Yes, in the first part, they are a level 2 unit for the Barbarians. A powerful unit!
On the third level. (goblins, orcs, wolves)
Hobbits were in parts 2 and 3 ;), I hope the question of hiring them wasn't considered...:) - because they definitely were available :)
In the 4th game, they are definitely with Haven, and in the 2nd game, they are with the Tower. But where are they in the 3rd game?? The Tower now has gremlins... could they be neutral units, but I don't remember...