Iconic Horror Scene: An American Werewolf in London (1981)

This scene is from the greatest werewolf movie of all time, An American Werewolf in London. No movie about lycanthropy will ever compare to this movie, and the majority of the reason for that is because of this scene. It features brilliant special effects by Rick Baker, and is the transformation scene that all other transformation scenes compare to.
It starts out with him sitting alone in his girlfriends apartment, then suddenly, something is wrong. He is in a lot of pain, and he starts taking off his clothes, so he is clearly also getting very hot. Then, comes one of my all-time favorite movie moments. You see his hand start to extend, starting the transformation.

Then, you see him start growing hair everywhere, and getting sharp teeth while his other limbs start to extend. The prosthetics in this scene are fan-fucking-tastic, especially when we see a full shot of him laying on the floor.

I love that we get a shot of the Mickey Mouse figurine before we get to the close-ups of his face changing. The close-up of his face could have looked totally cheesy if done by anyone else, but because it was Baker, it looks brilliant.

Now that every movie uses CGI, you don't really see practical effects like this anymore. Rick Baker won an Oscar this year for his make-up in the remake of the Wolf Man, but unfortunately the transformations were all CGI, so it didn't look nearly as cool.