Many stand-up comedians have transitioned into acting and have starred in popular movies and television shows, but they don't always display incredible acting - the roles are merely extensions of their routines and jokes. Here are the greatest acting performances by stand-up comedians that are sometimes funny, sometimes sad, sometimes both.

Many stand-up comedians have transitioned into acting and have starred in popular movies and television shows, but they don't always display incredible acting - the roles are merely extensions of their routines and jokes. Here are the greatest acting performances by stand-up comedians that are sometimes funny, sometimes sad, sometimes both.