Ob may refer to:

  • Ob River, a river in West Siberia, Russia
  • Ob Sea, an artificial lake on the Ob River
  • Ob, Russia, a town in Novosibirsk Oblast, Russia
  • Ob, Germany, place in Bidingen, Bavaria, Germany
  • Gulf of Ob, a bay of the Arctic Ocean in Northern Russia
  • Object Manager (Windows), a Windows NT subsystem
  • The fictional currency of the Gands in Eric Frank Russell's The Great Explosion