"Mr. Jester" is a science fiction short story by American writer Fred Saberhagen.
After a society without humor exiles their only comedian to the outskirts of the solar system, he becomes the only one who can save them from being destroyed by a Berserker.
"Mr. Jester" was a finalist for the 1967 Hugo Award for Best Short Story.
[1] Galactic Journey noted thematic parallels with Harlan Ellison's "'Repent, Harlequin!'
Said the Ticktockman", which had been published the previous month, but felt that Ellison's approach to the concept was preferable.