Proctor is an alternate dimensional counterpart of Dane Whitman, the Black Knight of Earth-616. Hailing from the line of Sir Percy of Scandia, the original Black Knight from the Age of Camelot, Whitman inherited the use of the Ebony Blade, a cursed sword forged by Merlin as the necessary dark mirror of the sword Excalibur. The blood curse on the Ebony Blade caused the wielder to develop a craving for shedding blood and other unwelcome side effects. At the time he encountered Proctor and the Gatherers, the Black Knight of Earth-616 had put aside the Ebony Blade in favor of a high-tech neuro-electric energy blade called the Sunsword, to avoid unnecessary bloodshed.
Although numerous examples of Dane Whitman or the Black Knight exist throughout the multiverse (even evil ones), the specific secondary identity of Proctor remains relatively unique to Earth-374. The only other identified Proctor appeared briefly in Ultraforce / Avengers #1 when a composite reality of multiple versions and merged expressions of those two teams existed. Black Knight-616 emerged into this strange world and killed a Proctor doppelganger who threatened with a version of the Ebony Blade. If this Proctor came from the same world as that blade, he may have been from a Nazi version of the Avengers, given the swastika on the hilt.