Presumably, they stole the show in Butch Cassidy and the Sundance Kid (7)
I believe the answer is:
robbers
I'm afraid I can't even guess how this answer relates to the clue.
Can you help me to learn more?
(Other definitions for robbers that I've seen before include "Thieves who threaten violence" , "Violent thieves" , "Thieves and burglars" .)