Bass-baritone
A bass-baritone is a male singer whose voice is quite low, like a deep baritone, but not quite as low as really deep bass.  People started to describe some singers as "bass-baritones" in the 19th century, particularly when the composer Richard Wagner wrote operas which needed singers with that kind of heroic voice.  Wagner's roles for bass-baritone include:  the Dutchman in Der fliegende Holländer, Wotan/Der Wanderer in the Ring Cycle and Hans Sachs in Die Meistersinger von Nürnberg. Wagner called these roles Hoher Bass ("high bass").