A Ouija board (from the French and German words for "yes", oui and ja, and usually pronounced /ˈwiːdʒiː/ in English), also known as a spirit board or talking board, is a flat board marked with letters, numbers, and other symbols, supposedly used to communicate with spirits. It uses a planchette (small heart-shaped piece of wood) or movable indicator to indicate the spirit's message by spelling it out on the board during a séance. The fingers of the séance participants are placed on the planchette, which then moves about the board to spell out messages.

Ouija is a trademark for a talking board currently sold by Parker Brothers. It has become a trademark that is often used generically to refer to any talking board.

Following its commercial introduction by businessman Elijah Bond in the late 1890s, the Ouija board was regarded as a harmless parlor game unrelated to the occult until American Spiritualist Pearl Curran popularized its use as a divining tool during World War I. Mainstream Christian religions and some occultists have associated use of the Ouija board with the threat of demonic possession and some have cautioned their followers not to use Ouija boards.

While Ouija believers feel the paranormal or supernatural is responsible for Ouija's action, it may be more parsimoniously explained by unconscious movements of those controlling the pointer, a psychological phenomenon known as the ideomotor effect. Despite being debunked by the efforts of the scientific community, Ouija remains popular among many young people.