Bonzo may mean:
- Self-immolation, a ritualistic suicide practice, often used to refer to suicide by fire
- Bonzo the dog, a fictional character that was created by British commercial artist George E. Studdy
- John "Bonzo" Bonham, the drummer for Led Zeppelin
- A chimpanzee - the title character in the 1951 comedy film Bedtime for Bonzo, also starring Ronald Reagan
- A nickname for Ronald Reagan, based on the film above and mentioned in a number of songs;
- Five Minutes by the band Bonzo Goes to Washington, which refers to a microphone test speech made by Reagan
- "My Brain Is Hanging Upside Down (Bonzo Goes to Bitburg)" by The Ramones
- Bad Time for Bonzo by The Damned
- The Bonzo Dog Doo-Dah Band
- Bonzo Madrid, a character in the Ender series.
- Uncle Bonzo, a menacing figure from Puccini's Madama Butterfly.
- An ex German prisoner of war recruited by Special Operations Executive during World War II
- Kooky; wacky; ridiculous. Ex. "Don't you find it bonzo that the man made such an enormous fortune from owning part of Hanna-Barbera."
- A brand of dog food.