Oc or OC may stand for:

• Orange County, California: a county south of Los Angeles; population about 3,000,000; home to such cities as Anaheim, Huntington Beach, Newport Beach, San Juan Capistrano, and San Clemente; and the setting of a popular television program (see below).
• The O.C., American television show set in the aforementioned Orange County in California.
• Optical Carrier levels in the SONET fiber-optic network specification
• Oakland County, MI.
• Oregon City, Oregon
• Occitan language
• Officer of the Order of Canada
• Overclocking
• oleoresin capsaicin, the active ingredient in pepper spray
• Ordis Corvus, a clan in the Browsergame Azuria
• Ocean City
• the art program openCanvas
• Street slang for Out of control