While not being a mini boss, the Bear is a unique enemy since he can only be found in a cave early in the game.
It is one of the strongest foes you'll encounter early on in the game. While it doesn't do alot of damage, it's total of 54 HP can be a problem for inexperienced players.
Upon defeating, it will drop Altan's Leather, a unique piece of leather armour granting a +15 health bonus.
Though not sure if intended, it's the only bear you can find in the Kingdom of Ehb.