A werebeast, or something similar, maintains personality while transformed.
Do We Have This One?? Usually, when a werebeast transforms, no matter how different they are, their mind is reduced to that of a mindless beast, without any kind of control. Therefore, you are understandably freaked out when a big old wolf-man explodes out of your friend. He walks up to you and swings his claws... ... and kills the Mook that was sneaking up on you. Right before calmly explaining that he's in control of his condition. Note that this isn't necessarily restricted to werebeasts; the Hulk has dipped into this trope on more than one occasion.
Hello, Unknown Troper. You'll need to get known to lend a hand here.