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.

Born in Chongqing, China in 1942, Doo moved with his family to Brazil, at age 8, and in 1963 got his first professional gig in Brazilian cinema, working as continuity supervisor in Amacio Mazzaropi's "O Cabeleira". He would go on to be assistant director in Mazzaropi's "O Puritano da Rua Augusta" (1965).

He had his directorial debut with 1978's "Ninfas Diabólicas", a mix of erotic and fantasy which would become his trademark style. Among his best known works are "O Gafanhoto" (an episode of the 1981 anthology film "Pornô!") and "O Pasteleiro" (a segment of 1981's "Aqui, Tarados!).

By the late 1980s Doo had given up filmmaking, but continued to appear as an actor in features by a number of Brazilian directors, such as Carlos Reichenbach's "Filme Demência" (1986), Ruy Guerra's "A Ópera do Malandro" (1986), and Guilherme de Almeida Prado's "A Dama do Cine Shanghai" (1987). In a coma after suffering from a stroke in 2009, Doo passed away in February, 2012.