Holo from Spice and Wolf.
Tio from Arifureta, though I would not recommend watching it.
The entire cast of Busou Shinki depending on your definition of transformation.
Certain characters in Freezing. Wouldn't recommend this one either.
Eureka Seven.
So I'm a Spider, So What, but please don't bother.
Medaka Box. Read the manga instead.
Overlord has multiple characters that fit.
Rosario to Vampire has Moka. Don't bother.
That Time I Got Reincarnated as a Slime has multiple characters.
Why is it that he can hit a 3rd baseman on a frozen rope from 300 feet away, but he can't hit a 12 foot tall catcher from 60 feet 6 inches away?
-Awesomeo_4000