Diactorism

The phenomenon that occurs when you realize you've been conflating two or more different actors or actresses as a single person. Most common with young actors before they make it big or character actors.

Common examples:
Shia Labeouf and Topher Grace
Kurt Russell and Patrick Swayze
Rachel Bilson and Mila Kunis
Omar Epps and Mekhi Phifer and Sean Patrick Thomas

I had serious diactorism this morning when I realized Shia Labeouf wasn't on That 70s Show. Turns out Topher Grace is a different guy.

by Jmdickinson January 27, 2015