Bass/Basso: The lowest male voice, generally with a range from E2 to E4. Typically plays elderly figures, villains, kings or fathers. Example: Samuel Ramey.
Baritone/Baritono: Middle-ranged male voice type with range approximately F2 to F4. Often heroes or noblemen in operas involving love or war. Examples: Dmitri Hvorostovsky, Thomas Hampson
Tenor/Tenore: The highest non-falsetto male voice typically ranging from C3 to C5. Usually play young, heroic roles but occasionally villains and comedians. Examples: Enrico Caruso, Pavarotti.
Countertenor/Contraltista: Highest male voice; vocal range similar to female mezzo-soprano or contralto voice types. These roles were originally written for castrati: Male singers castrated before puberty in order to retain a soprano or even higher voice. Examples: David Daniels, Andreas Scholl
Heldentenor/Tenore Robusto: A "heroic" tenor with more power, volume and resonance in the dramatic upper part of the range. Can have range and tessitura similar to baritones but with tenor range and timbre. Usually sing heroically dramatic roles.
Examples: Lauritz Melchior, Giuseppe Giacomini