An octave is the interval between one musical pitch and another with half or double its frequency.

Octave may also refer to:

• Octave (album), by The Moody Blues
• Octave (poetry), a verse form consisting of eight lines of iambic pentameter
  • Sicilian octave, a verse form consisting of eight lines of eleven syllables each
  • Ottava rima, an Italian verse form
• Octave, a fictional character in the film Interstella 5555: The 5tory of the 5ecret 5tar 5ystem

• Octave (electronics), a logarithmic unit for ratios between frequencies
• GNU Octave, a high-level computer programming language
• Octave, an IT risk management method
• Octonion, originally octave, in hypercomplex algebra

• Octave (given name) including a list of people with the name
• Octave (musician) (born 1963), Romanian rock musician
• Dieuson Octave (born 1997), American rapper known as Kodak Black

• Octave, Arizona, a place in the US
• Octave (horse) (foaled 2004), a thoroughbred racehorse
• Octave (liturgy), either the eighth day after a feast, or the whole period of those eight days
• Octave celebration, a religious celebration in Luxembourg
• Octave (unit), a British unit for measuring whisky
• Hurricane Octave, several tropical storms

• All pages with titles beginning with Octave
• Octave band, a frequency band that spans one octave
• Law of Octaves, a concept from the history of the development of the periodic table of chemical elements