During the 1970s, Assante was a regular on two NBC soap operas,
How to Survive a Marriage as Johnny McGhee and
The Doctors as Mike Powers. His first film was
The Lords of Flatbush (1974), although his work did not appear in the final cut of the film and the end credits misspelled his last name as Assanti. He starred in
Prophecy (1979). His first on-screen role was playing Sylvester Stallone's brother in
Paradise Alley. A role that brought him greater attention came in 1980's
Private Benjamin, as a handsome Frenchman who becomes the love interest of a U.S. soldier played by
Goldie Hawn. In 1984, he portrayed the playboy violin virtuoso Maximillian Stein in the
Dudley Moore comedy vehicle
Unfaithfully Yours. Assante has played a number of tough hero characters, such as his starring role as private eye
Mike Hammer in the film
I, the Jury (1982) as well as mafia gangsters such as Michael Moretti in ''Sidney Sheldon's Rage of Angels''. In 1990, his role as Roberto Texador in
Sidney Lumet's film
Q&A garnered him a Golden Globe nomination. The following year, he portrayed
Bugsy Siegel in
Neil Simon's
The Marrying Man (1991). The following year, he was seen as mafia boss Carol D'Allesandro in
Hoffa (1992) starring
Jack Nicholson, and crime kingpin
John Gotti in the 1996 made-for-television biopic
Gotti, for which he won a
Primetime Emmy Award for Outstanding Lead Actor in a Miniseries or a Movie. In addition to mafia and "tough-guy" roles, Assante has appeared in historical dramas, such as Napoleon Bonaparte in 1987's
Napoleon and Josephine: A Love Story opposite
Jacqueline Bisset, Odysseus in
The Odyssey, Friedrich Nietzsche in the film adaptation of Irving Yalom's novel
When Nietzsche Wept, and as Sanchez, Queen Isabella's Minister of State, in
1492: Conquest of Paradise. Other film appearances include one as a Cuban bandleader in
The Mambo Kings opposite
Antonio Banderas and in the adaptation of the science-fiction story
Judge Dredd with
Sylvester Stallone, his co-star in
Paradise Alley. He appeared in the 2007 film
American Gangster with
Denzel Washington and
Russell Crowe. He had a recurring guest star role in several episodes of
NCIS, playing the international arms dealer
René Benoit. He has also appeared in the 2009 horror film
Smile as the mysterious Tollinger and portrayed Ernie in
Sugar (marketed on
Lifetime as
Danger Below Deck). Outside of the U.S., he has participated in several film projects and humanitarian endeavors in
Romania,
Bulgaria,
North Macedonia,
Serbia,
Croatia,
Bosnia-Herzegovina,
Kazakhstan, and
Uzbekistan. ==Personal life==