Tarkus

Tarkus is an antagonist from Part I: Phantom Blood. He is a vampire made from the centuries-old corpse of a powerful warrior of ancient Britain. Unlike his ally Bruford, Tarkus was a typical strongman fighter and had sold his entire soul to Dio Brando.

History
Tarkus and Bruford were successful in The Challenge of the 77 in 1563 (two of only five challengers to ever succeed) (Chapter 28, p. 11). Tarkus and Bruford were members of the Tudor Dynasty and retainers of Mary Stuart. Eventually they were beheaded for their support of Mary against her rival Elizabeth, giving themselves over to save Mary. However, Elizabeth's deception to make them surrender led to a strong sense of betrayal that made them susceptible to manipulation by Dio.

Phantom Blood
The pair is known as "The Dark Knights" and were eventually resurrected as vampires by Dio so that they could oppose Jonathan Joestar, Will. A. Zeppeli, and Robert Speedwagon.

Tarkus showed little respect for Bruford after the latter's defeat and rehabilitation during his battle with Jonathan Joestar. He also killed Zeppeli for attempting to help Jonathan, but was killed by the latter shortly after.