Guido Mannari moved to Rome at a young age and decided to pursue a career as an actor, inspired by the movie Il sorpasso, which was filmed in Castiglioncello, his native town.

After playing in the avant-garde theatre for a short time in the capital, he decided to go to the United States for a year in order to master his future profession.

Spending a year in America, he returned to Italy and made his first debut in Arabella (1967) directed by Mauro Bolognini.

The scene was repeated several times: as the actress was thrown to the ground and pressed slaps by Guido Mannari, Omaggio hit her head on the asphalt, losing consciousness, but was rescued by director Bruno Corbucci, who was directing the filming.

In a scene in which Macro swears his allegiance to Caligula, Mannari held his arm over an open flame long enough to be severely burned.

[3] Guido Mannari was in a relationship with Elizabeth Taylor, with whom he got an acquaintance during the filming of the movie The Driver's Seat in 1974.