If you are not familiar with Charlie's antics on 'It's Always Sunny,' he is best known on the show for his bad hygiene, rat-hunting abilities, and pretending to be a lawyer.
Hit the jump to find out what role Day would end up playing as well as what we already know about the film.
Day is currently in talks to play a professor. The movie, which already includes fellow FX star Charlie Hunnam from 'Sons of Anarchy,' is about an alien invasion on earth where humans are forced defend themselves using huge robots.
Although he will be in a robot vs. alien flick that's going to be pretty action-heavy, we have to assume Day will be providing a little comic relief.
What are your thoughts on Charlie Day being in an alien invasion movie?