A shtick (Yiddish: שטיק) is a comic theme or gimmick. The word entered the English language from the Yiddish shtik (שטיק), related to German Stück and Polish sztuka (all ultimately from Proto-Germanic *stukkiją), all meaning "piece", "thing" or "theatre play"; "Theaterstück" is the German word for play (and is a synonym of "Schauspiel", literally "viewing play" in contrast to the "Singspiel").

The English word "piece" is sometimes used in a similar context (for example, a musical piece). In stand-up comedy context a near equivalent term is a "bit". Another variant is "bits of business" or just "bits". Shtick may refer to an adopted persona, usually for comedy performances, that is maintained consistently (though not necessarily exclusively) across the performer's career. In this usage, the recurring personalities adopted by Laurel and Hardy through all of their many comedy films (although they often played characters with different names and occupations) would qualify as their shtick. A comedian might maintain several different shticks of this sort, particularly if appearing in a variety show encouraging development of multiple characters, such as Saturday Night Live.

In common usage, the word shtick has also come to mean any talent, style, habit, or other eccentricity for which a person is particularly well-known, even if not intended for comedic purposes. For example, a person who is known locally for an ability to eat dozens of hot dogs quickly might say that it was his shtick. Among Orthodox Jews, "shtick" can also refer to wedding shtick, in which wedding guests entertain the bride and groom through dancing, costumes, juggling, and silliness.

Many fictional characters have more thematic shticks. This is particularly true of comic book villains, who are almost always seen wearing a particular costume and behaving in ways that are consistent with a bizarre and psychotic obsession. The supervillains of Batman (collectively known as the Rogues Gallery) are especially notorious for this (see below). There are also many professional wrestlers who deliver memorable catchphrases, and/or enter arenas performing signature gestures to the tune of thematically appropriate songs, causing crowds to laugh and cheer (see below).

Because of its roots in show business, shtick has taken on the connotation of a contrived and often used act. For this reason, journalists and commentators often apply the word disparagingly to stock replies from politicians.