1. Enrico Caruso (1873-1921): Italian operatic tenor, one of the most famous and influential singers of all time.
2. Placido Domingo (born 1941): Spanish operatic tenor, baritone, conductor, and arts administrator.
3. Fedor Chaliapin (1873-1938): Russian operatic bass who was equally well-known as an actor and director.
4. Nicolai Gedda (1925-2017): Swedish operatic tenor and one of the most successful singers of the 20th century.
5. Mario Lanza (1921-1959): American operatic tenor and Hollywood film star.
6. Jussi Björling (1911-1960): Swedish operatic tenor who is considered one of the greatest tenors of all time.
7. Luciano Pavarotti (1935-2007): Italian operatic tenor and one of the most popular singers of all time.
8. Beniamino Gigli (1890-1957): Italian operatic tenor who was one of the most famous and successful singers of the early 20th century.
9. Tito Schipa (1888-1965): Italian operatic tenor and one of the most popular singers of the early 20th century.
10. Richard Tauber (1891-1948): Austrian operatic tenor and operetta singer who was extraordinarily successful in the early 20th century.
This list is of course subjective, and there are many other great male opera singers who could have been included.