A Mime is a member of a third-party faction that wins only if all of its members are voted out, or eliminated. The Mime faction also has a factional Roleblock that can be used at Night to hopefully stop the Mafia's kill. If the Mime faction wins, the game usually ends.
This role is used in the Open setup Paris Mafia.
Use and Power
Mimes are generally not used outside the aforementioned Open setup because if a single one of them gets killed (i.e. not eliminated), all of them lose. That's not particularly fair. That said, see The Game of the Year, where Mimes were successfully used to deter shoot-from-the-hip eliminating (and unfortunately lost day 1 due to Angels).