Have you ever watched a movie and only realized afterward that the leading actoress/actor in the movie wasn't who you thought they were?

I just finished watching a movie called Frozen River. I thought the leading actress was Susan Sarandon, but she wasn't. It was an actress by the name of Melissa Leo. Melissa Leo, looks like Susan Sarandon, imo.

Susan Sarandon http://www.imdb.com/media/rm2205257216/nm0000215
Melissa Leo http://www.imdb.com/media/rm2545978112/nm0502425