Octavian was the name of Augustus (63 BC – 14 AD) before he became Emperor of Rome.
Octavian or Octavianus may also refer to:
- Octavian (horse), a British horse
- Octavian, an octopus villager from the video game series Animal Crossing
- Octavian (rapper), French-British rapper
- Octavian (romance), a 14th-century Middle English poem
- Octavians, financial commissioners in 16th century Scotland
- Octavian, a character in Der Rosenkavalier
- Octavian or Gus, a mouse in Cinderella
- Octavian, a Camp Half-Blood character
- Octavius, Latin praenomen (first name)