Hopkins is a historical figure from the early 1600s. He was an English lawyer who took up the occupation of witch hunting, giving himself the self-appointed title of "Witchfinder General." Within three years of activity, there were three hundred people hanged as witches in England by his hand. It is believed he died before reaching old age, long before the Salem Witch Trials, but there are theories that he survived.
The Hopkins of the Salem Grand Order is not a Servant, but rather an out of place living human brought forth by the machinations of Raum. Sanson believes he would be suited as an Anti-Hero, but it is not confirmed if he qualifies as a Heroic Spirit.