John Greyson is a Canadian director, writer, video artist, producer, and political activist, whose work frequently deals with queer characters and themes. He was part of a loosely affiliated group of filmmakers to emerge in the 1980s from Toronto known as the Toronto New Wave.

Zero Patience is a 1993 Canadian musical film written and directed by John Greyson. The film examines and refutes the urban legend of the alleged introduction of HIV to North America by a single individual, Gaëtan Dugas. Dugas, better known as Patient Zero, was the target of blame in the popular imagination in the 1980's in large measure because of Randy Shilts's American television film docudrama, And the Band Played On (1987), a history of the early days of the AIDS epidemic. Zero Patience tells its story against the backdrop of a romance between a time-displaced Sir Richard Francis Burton and the ghost of "Zero".