Francesco 'Nino' Castelnuovo, a talented individual, was born in Lombardy, Italy, as the second of four brothers to humble beginnings. He embarked on a series of occupations, including house painting, mechanic work, and sales agent, before deciding to pursue his passion for drama at the renowned Piccolo Teatro in Milan.
His cinematic journey began in 1957 with a screen appearance, followed by a motion picture debut two years later. Although his early roles were limited, his career gained momentum with a co-starring role opposite Catherine Deneuve in the romantic musical drama The Umbrellas of Cherbourg (1964). Although his scenes were re-dubbed, this marked a significant turning point in his career.
Castelnuovo's greatest success came through his work on television, particularly in the mini-series I promessi sposi (1967),where he played the pivotal role of Renzo Tramaglino. Set during the Spanish occupation of Lombardy in the 17th century, this period drama was based on a best-selling novel by Alessandro Manzoni.
Throughout his career, Castelnuovo appeared in various American and Italian-produced westerns, often featuring cosmopolitan casts. By the early 1970s, he focused primarily on stage work, serial television, and commercials, notably for Olio Cuore, a corn oil company.
Castelnuovo's final international appearance was a small role in The English Patient (1996) as an archaeologist, remembered in flashback scenes by the lead character Almásy. He retired from acting in 2016 and was married to the actress Danila Trebbi.