Happenstance is a portmanteau of 'happening' and 'circumstance'. It generally refers to a random event. The word has been in use since the 19th century.
It may also refer to:
- Happenstance (CSI episode), a season seven episode of the American crime drama, CSI
- Happenstance, a novel by Canadian author Carol Shields
- Happenstance, a song by The dB's from their 1982 album, Repercussion.
- Happenstance (film), a French film by Laurent Firode
- Happenstance (Fozzy album), a 2002 album
- Happenstance (Rachael Yamagata album), a 2004 album
- Happenstance (Boyracer album), a 2004 album
- Happenstance (Independent pop/rock/powerpop band based in Sydney, Australia), a band
- Happenstance (Webisode), Dr. Horrible's Sing-Along Blog by Joss Whedon