Record of Ragnorok (Snake Monster Transformation)

 Episode 7 has an accusing serpent-man transform in anger over Adam's interference with his rigged trial:

Tekken (Demon Transformation)

Thanks to Ian Ricky for editing and supplying this compilation of demon transformation scenes from the Tekken video game series. The character Jin Kazama turns into a demon on several occasions after being consumed by the "Devil Gene."

0:00 1st TF

0:06 2nd TF (Comic)

0:59 3rd TF

1:48 1st Revert

3:12 2nd Revert

3:43 4th TF & 3rd Revert

04:45 5th TF 

President Werewolf #2 (Werewolf Transformation)

 In issue #2 the president transforms during a congressional session on the night of a full moon; he rips apart the Speaker of the House but keeps his tie on.