Shadow Knight AKA Randall Spector is a villain that's an enemy to Moon Knight. He's Moon Knight's brother, who was hospitalized and went insane.
Randall Spector once was a mercenaries along side his brother for the CIA. When the two brothers went to Italy for gun running mission, Randall intended to sell out to their opposition and killed Lisa, a woman with whom Marc was involved. Before dying, Lisa told Marc of Randall’s betrayal, and Marc fought Randall, ultimately bringing him down with a grenade. Because of this, Randall was Hospitalized for months. Due to a Brain injury Randal went insane and became an enemy to Moon Knight.