J.B. is a 1958 play by Archibald MacLeish, set in a modern circus. Two vendors, Mr. Zuss and Nickles, begin the play-within-a-play by assuming the roles of God and Satan, respectively. They watch J.B., a wealthy banker, describe his prosperity as a just reward for his faithfulness to God. Scorning, Nickles challenges Zuss that J.B. will curse God if his life is ruined. The vendors observe as J.B.'s children and property are destroyed in horrible accidents and the former millionaire takes to the streets. J.B. is visited by three Comforters (representing History, Science, and Religion) who offer contradicting explanations for his plight. He declines to believe any of them, instead calling out to God to show him the just cause for his punishment. When finally confronted by the circus vendors, J.B. refuses to accept Nickles' urging toward suicide to spite God or Zuss' offer of his old life in exchange for quiet obedience to religion. Instead, he takes solace in his wife Sarah and the new life they will create together.

As a play, J.B. went through several incarnations before it was finally published. MacLeish began the work in 1953 as a one-act production but within three years had expanded it to a full three-act manuscript. The resulting work won the 1959 Pulitzer Prize for Drama. There are two versions available: the original book (published by Houghton Mifflin Harcourt) and the script which MacLeish revised substantially for Broadway (published by Samuel French Inc.).