Chien Lien Tu, best known by his stage name John Doo, was a Chinese-Brazilian filmmaker, director of photography screenwriter, producer, and occasional actor.

Doo was part of a recurring team of filmmakers, actors and producers in São Paulo's "Boca do Lixo", a downtown square that became a pole of production and distribution of erotic and pornographic films. Among the highlights of his career are partnerships with David Cardoso and Ody Fraga, the three of them collaborating in a series of anthology erotic films.