Actor James Gandolfini, who made the ruthless mob boss Tony Soprano one of the great television characters of all time, has died at age 51.

The New Jersey-born actor died of a suspected heart attack while on holiday in the Italian capital, Rome.

He was cast in 1999 as the lead in The Sopranos, David Chase's dramatic series for HBO about a suburban Mafioso in therapy.

The show made him a star, earning him three Emmy awards for outstanding lead actor in a drama series.

By the time the show finished its sixth and final season in 2007, Gandolfini was earning a reported $1 million per episode.

Gandolfini, who was a character actor, also had supporting roles in films including Get Shorty, The Mexican and Zero Dark Thirty.

He was married to Deborah Lin and the couple had a baby girl last October.

He has a son from a previous marriage.