A butler was a male individual who was hired to perform household tasks in another's home.
In 2369, Beverly Crusher sought out Jean-Luc Picard to play the role of the butler in her play, Something for Breakfast. The role had only two lines. She thought he would be excellent for the role, although Picard was disappointed he was not considered for a leading role, even though he did not have the time to learn one. (TNG: "A Fistful of Datas")