- O Brother, Where Art Thou?: Three refugees from a chain gang re-enact The Odyssey in the Depression-era South.
- Ocean's Eleven: Man tries to get some money while humiliating his ex's current affair.
- Oculus: An evil mirror kills people...or does it?
- Office Space: One guy stops caring about his job, another wants to rob his employer, and a third just wants his stuff back.
- Oliver!: Prepubescent exceeds alloted institutional dietary requirements, which leads to him being sold as property and getting involved with thieves, hookers and psychopaths. It's a musical.
- The Omen (1976): Satan puts his son up for adoption. Murder ensues.
- On the Town: Gene, Frankie and some third guy have one day to see NYC.
- Once: A multi-cultural couple should get together for love of a vacuum cleaner, but they don't.
- Once Upon a Time in the West: A former criminal helps a dying crippled man accomplish his final wish in exchange for gaining a legitimate position in the crippled man's company. However, the former criminal's past comes back to haunt him in the form of a guy who plays the harmonica.
- Or: Woman moves to the wild West to meet new family, gets Unwanted Harem. Not a romantic comedy.
- A Fistful of Dynamite: Man becomes an Accidental Hero while his partner blows up anything he sees.
- Once Upon a Time in America: The histories of a group of former juvenile delinquents is explored. This is a movie about New York gangsters directed by a man famous for westerns.
- One Flew Over the Cuckoo's Nest: A petty criminal feigns insanity to get out of prison and is sent to a mental hospital, where he teaches the residents to play basketball and fish, and gives them chewing gum.
- One Hour Photo: Robin Williams works at a Wal-Mart clone and spends most of his time alone watching The Simpsons. It's a dramatic thriller.
- Onward: A family film about two brothers want to resurrect their dead father.
- Orphan: A little girl is older than she looks.
- The Orphanage: Woman goes back to her childhood home, where her young son befriends some of her old friends from childhood.
- The Others: Woman is pestered by the new inhabitants of her house.
Better Than It Sounds / Film O