Opus the penguin is a large-nosed, existentialist penguin, a main character in the Bloom County comic strip series and later work by Berke Breathed. Opus usually wears only a bow tie and collar, though he switched to a regular diagonally striped necktie when running for vice president. He sometimes wears straw boater hats with fruit. Occasionally he walks around in his briefs.

Opus was originally introduced as a one-time gag about anxiety-ridden Mike Binkley bringing home what he thought was a German Shepherd, which turned out to be a penguin, much to the consternation of Binkley's father.

Over the years, Opus has served as Steve Dallas' legal secretary, journeyed to Antarctica in search of his mother, played the tuba in heavy metal group Deathtöngue (later renamed Billy and the Boingers), wooed an abstract sculptor named Lola Granola, worked as a newspaper personals editor, lifestyle columnist and comic strip writer, and run for vice president on the National Radical Meadow Party ticket, along with his running mate Bill the Cat. In the tradition of many other popular characters, Opus apparently died (while unwillingly brought along on a balloon expedition to Washington, DC to zap the ambassador from apartheid-era South Africa with a ray that would temporarily turn him black) only to return with amnesia. He later regained his memory after being in a state of intense and total shock; he heard that Diane Sawyer married Eddie Murphy.

Opus was the first Bloom County regular to appear in the Outland strip, and also appeared in some of Berke Breathed's children's books.

Opus returned in a Sunday exclusive strip simply titled with the main character's name, Opus in 2003. The first few strips showed Opus's discontent living in Antarctica with his overbearing mother. A misdirected Mars probe happened to give him the means to return to Bloom County, where he set about looking for his old friends. Binkley apparently became a teen eunuch in Tibet. Also, it is hinted that Bill the Cat's rotting carcass was the source of the recent bovine spongiform encephalopathy epidemic.

Opus is apparently a king penguin, although one strip has him labeled as a "red-nosed magellanic flatfanny."