A perfectly timed, short, witty remark. Used to put someone in their place, put someone down, make a humorous remark or observation, or to simply show the world how awesome you are.
The best One Liners make use of that wonderous language device the pun as well as sheer wit and good timing.
Commonly used by many great actors in action movies
1) Arnold Schwarzenegger in Predator
after getting someone with a thrown knife which stuck the man to the wall:
2) Arnold (again) in Commando after dangling Sully (one of the villians) off of a cliff and then letting him drop:
"What Happened to Sully?"
"I let him go."
3) John Wayne in The War Wagon after he and his partner shoot two bad guys at once:
partner: "Mine hit the ground first!"
John Wayne: "Mine was taller."