Galileo is a 1975 biographical film about the 16th- and 17th-century scientist Galileo Galilei, whose astronomical observations with the newly invented telescope led to a profound conflict with the Roman Catholic Church. The film is an adaptation of Bertolt Brecht's 1943 play of the same name. The film was produced by Ely Landau for the American Film Theatre, which presented thirteen film adaptations of plays in the United States from 1973 to 1975. Brecht's play was recently called a "masterpiece" by veteran theater critic Michael Billington, as Martin Esslin had in 1960. The film's director, Joseph Losey, had also directed the first performances of the play in 1947 in the US — with Brecht's active participation. The film is fairly true to those first performances, and is thus of historical significance as well.

The Galileo affair began around 1610 and culminated with the trial and condemnation of Galileo Galilei by the Roman Catholic Inquisition in 1633. Galileo was prosecuted for his support of heliocentrism, the astronomical model in which the Earth and planets revolve around the Sun at the centre of the universe.