For actors, co-starring in a movie or TV series together can mean months or even years of working very, very closely.
So if you don't... like each other, well that's got to be hard. Especially if your characters are besties, or in relationships.
In some cases, perhaps the best acting of someone's career is acting like they don't find their castmate insufferable.
Here are a number of co-stars you may not know don't exactly get on in real life like their characters did on screen.