Charles Billy is an American singer who is best known as the lead vocalist for thrash metal band Testament.

Sadus is an American thrash metal band from Antioch, California, active from 1985[A] to 2015, and reunited in 2017. Originally a quartet, the band's sound fuses thrash metal with death metal, featuring highly technical musicianship. They are known for the unique death growl of vocalist Darren Travis, and bassist Steve Di Giorgio. During their career, Sadus has released six studio albums, one compilation album and four demos, and had two lineup changes, with the band continuing without replacing any of the departed members.