Snake Jafar

Snake Jafar is a form of the villain from Aladdin. Jafar boasts that he is "the most powerful being on Earth", which causes Aladdin to call him a cowardly snake. As a twisted reply to that insult, Jafar turns into a snake. Aladdin and Jafar are fighting until Aladdin convinces him that Genie is more powerful than he will ever be. Faced with this realization, Jafar uses his final wish to become Genie Jafar.

Aladdin
Aladdin, Abu and Carpet set off to the palace to defeat Jafar and during a battle Jafar decides to turn himself into a snake in order to kill Aladdin easily. Snake Jafar is stabbed twice and just when Jafar nearly squeezes Aladdin to death Aladdin tricks Jafar into wishing to be a genie.

Aladdin: The Game
In both versions of the Aladdin video game, Snake Jafar is the final boss.

Fantasmic!
Jafar turns himself into a snake in the live show Fantasmic! in his attempt to destroy Mickey Mouse.