Theodoros "Theo" Angelopoulos (Greek: Θεόδωρος Αγγελόπουλος; (27 April 1935 – 24 January 2012) was a Greek filmmaker, screenwriter and film producer. He dominated the Greek art film industry from 1975 on, and Angelopoulos was one of the most influential and widely respected filmmakers in the world. He started making films in 1967. In the 1970s he made a series of political films about modern Greece.

Angelopoulos' films, described by Martin Scorsese as that of "a masterful filmmaker", are characterized by the slightest movement, slightest change in distance, long takes, and complex, carefully composed scenes. His cinematic method is often described as "sweeping" and "hypnotic." Angelopoulos has said that in his shots, “time becomes space and space becomes time.” The pauses between action or music are important to creating the total effect.

In 1998 his film Eternity and a Day went on to win the Palme d'Or at the 51st edition of the Cannes Film Festival, and his films have been shown at many of the world's esteemed film festivals.

Theodoros Angelopoulos was born in Athens on 27 April 1935. His father Spyros hailed from the town of Ampeliona, Messenia in the Peloponnese. During the Greek Civil War, his father was taken hostage and returned when Angelopoulos was 9 years old; according to the director, the absence of his father and looking for him among the dead bodies (during the "Dekemvriana" in Athens) had a great impact on his cinematography. He studied law at the National and Kapodistrian University of Athens, but after his military service went to Paris to attend the Sorbonne. He soon dropped out to study film at the Institut des hautes études cinématographiques (IDHEC) before returning to Greece. There, he worked as a journalist and film critic. Angelopoulos began making films after the 1967 coup that began the Regime of the Colonels. He made his first short film in 1968 and in the 1970s he began making a series of political feature films about modern Greece: Days of '36 (Meres Tou 36, 1972), The Travelling Players (O Thiassos, 1975) and The Hunters (I Kynighoi, 1977). In 1978, he was a member of the jury at the 28th Berlin International Film Festival.

Theo Angelopoulos is a masterful filmmaker. He really understands how to control the frame. There are sequences in his work—the wedding scene in The Suspended Step of the Stork; the rape scene in Landscape in the Mist; or any given scene in The Traveling Players—where the slightest movement, the slightest change in distance, sends reverberations through the film and through the viewer. The total effect is hypnotic, sweeping, and profoundly emotional. His sense of control is almost otherworldly.

He quickly established a characteristic style, marked by slow, episodic and ambiguous narrative structures as well as long takes (The Travelling Players, for example, consists of only 80 shots in about four hours of film). These takes often include meticulously choreographed and complicated scenes involving many actors.

His regular collaborators include the cinematographer Giorgos Arvanitis, the screenwriter Tonino Guerra and the composer Eleni Karaindrou. One of the recurring themes of his work is immigration, the flight from homeland and the return, as well as the history of 20th century Greece. Angelopoulos was considered by British film critics Derek Malcolm and David Thomson as one of the world's greatest directors. Famous film directors including Werner Herzog Emir Kusturica, Akira Kurosawa, Ingmar Bergman, Wim Wenders, Dušan Makavejev, William Friedkin, Manoel de Oliveira, Michelangelo Antonioni among others, were also admirers of his works.

While critics have speculated on how he developed his style, Angelopoulos made clear in one interview that "The only specific influences I acknowledge are Orson Welles for his use of plan-sequence and deep focus, and Mizoguchi, for his use of time and off-camera space." He had also cited Andrei Tarkovsky's 1979 work Stalker as an influence.