Mastroianni labored through bigger and bigger roles in more than 20 Italian films before getting the chance to showcase his wry, world-weary appeal in "Tempi Nostri" and "Cronaca dei Poveri Amanti" (both 1954). He worked for the first time with director Vittorio De Sica and co-star Sophia Loren in the crime comedy "Peccato che Sia una Canaglia/Too Bad She's Bad" (1955). Mastroianni and Loren went on to co-star in another eleven films, including De Sica's "Ieri, Oggi, Domani/Yesterday, Today and Tomorrow" (1963) and "Matrimonia all'italiana/Marriage--Italian Style" (1964), for which he received a Best Actor Oscar nomination, the social drama "Una Giornata Particolare/A Special Day" (1977), which earned him a second Oscar nomination, and Robert Altman's unsuccessful all-star "Pret-a-Porter (Ready-to-Wear)" (1994).
By the late 1950s, Mastroianni was a major Italian star, but was little-known in the US until he appeared as a decadent gossip columnist in Federico Fellini's classic "La Dolce Vita" (1960). This sexual, symbolic and hallucinogenic film swept the world, as did its star. Mastroianni went on to function as Fellini's chief protagonist and mouthpiece in films from "8 1/2" (1963) through "Intervista" (1987). He also held a position as one of the most versatile international stars of the 60s, notably in the labor drama "I Compagni/The Organizer" (1963) and Visconti's adaptation of Albert Camus' existential exploration, "The Stranger" (1967). Mastroianni has brought a similar verve to his later, middle-aged parts in films such as "Allonsonfan" (1975), "Gabriela" (1983) and especially Nikita Mikhalkov's "Dark Eyes" (1987). The latter, adapted from short stories by Anton Chekhov, provided the actor with a tour-de-force role as an architect who has settled into a life of wealth through marriage and earned him another Best Actor Oscar nod.
An appearance in the US-made feature "Used People" (1992) did not adequately showcase Mastroianni's talents; he was virtually wasted as a charmer romancing recent widow Shirley MacLaine. Mastroianni made his final film appearance in Manoel de Oliveira's "Journey to the Beginning of the World" (1997). Much as the actor had been Fellini's stand-in, in this film, he portrayed an aging film director named Manoel. The actor's longtime companion, Anna Maria Tato, shot the documentary "Marcello Mastroianni: I Remember, Yes I Remember" (1997) during filming of "Journey", which serves as both tribute to and summary of the actor's life and career.