The Knights Who Say "Ni!", also called the Knights of Ni, are a band of knights encountered by King Arthur and his followers in the 1975 film Monty Python and the Holy Grail and the play Spamalot. They demonstrate their power by shouting "Ni!", terrifying the party, whom they refuse to allow passage through their forest unless appeased through the gift of a shrubbery.

Monty Python and the Holy Grail is a 1975 British comedy film satirizing the Arthurian legend, written and performed by the Monty Python comedy group and directed by Gilliam and Jones in their feature directorial debuts. It was conceived during the hiatus between the third and fourth series of their BBC Television series Monty Python's Flying Circus.