Julius Caesar was a play written by William Shakespeare, generally considered a classic of Human literature, based on the life of Gaius Julius Caesar, a military and political leader of the Roman Republic of ancient Earth.
In 2293, General Chang quoted lines from the play including "If you have tears, prepare to shed them now."; "Cry 'havoc!' and let slip the dogs of war!"; and "I am as constant as the northern star" while his Bird-of-Prey attacked the USS Enterprise-A over Khitomer. (Star Trek VI: The Undiscovered Country)
Julian Bashir introduced Elim Garak to the play in 2371. Garak first claimed to find it farcical, telling Bashir he didn't "see the value" of Shakespeare's work, as well as claiming to know that Brutus "...was going to betray Caesar in the first act, but Caesar didn't figure it out until the knife was in his back." (DS9: "Improbable Cause")
A short time later, however, Garak had apparently revised his opinion at least somewhat, when choosing to paraphrase a passage from the play to Enabran Tain in effort to explain the failure of a joint Obsidian Order-Tal Shiar task force to anticipate the Dominion surprise counter-attack that subsequently destroyed it: "I'm afraid the fault, dear Tain, is not in our stars... but in ourselves. Something I learned from Doctor Bashir." (DS9: "The Die is Cast")