Which character sings “I Have But One Heart” at Connie’s wedding in The Godfather?

Johnny Fontane sings “I Have But One Heart” at Connie’s wedding in The Godfather.

Fontane is a famous singer and actor who attends the wedding of Connie Corleone and Carlo Rizzi. The song is performed by Al Martino, who plays Fontane, and the moment helps establish the character’s celebrity status within the Corleone family’s circle.

The song is an English version of the Italian standard “Un Cuore Solo.” It is heard during the wedding sequence, one of the film’s best-known openings, which introduces the family and many of its relationships.

This answer is sometimes confused with Al Martino, the actor and recording artist who performs the song. The character is Johnny Fontane; the performer is Martino.