Situated between the contralto and baritone, the tenor usually plays the male lead in opera and musical theater, usually a young romantic hero.
Many pop singers are tenors, although the vocal subcategories used in opera are not applied to them. Examples include Justin Timberlake, Clay Aiken, Adam Lambert, Matthew Morrison, Darren Criss, Chord Overstreet, Freddy Mercury, Steven Tyler, and Adam Pascal.
countertenor: has the same singing as speaking voice as a regular tenor, but his natural range is in the alto (or even soprano) register.
Leggiero ("light") tenor: flexible voice with a very high range, he's a vocal acrobat.
Lyric tenor: A strong, sweet, lightweight voice usually reserved for the boy next door and other vulnerable, naive charcters. Examples include Roberto Alagna and Luciano Pavarotti.
Spinto tenor: A lyric voice with a strong dramatic edge, a bridge between lyric and dramatic. Examples include Placido Domingo and Mario Lanza.
Dramatic tenor: A powerful, emotive, edgy voice which is suited to bold, tragic heroes. Examples include Mario del Monaco and Jose Cura
The countertenor has the normal range, speaking and singing, as a regular tenor, but is capable of singing in the contralto, mezzo-soprano, and, sometimes, even soprano ranges. They use falsetto, rather than their lower range, when singing.
The lyric tenor is the lighter, sweeter sounding, while the dramatic tenor has a stronger, richer, more heroic voice.