The Occult Researchers are a group of researchers that specializes in the field study of the paranormal, they are led by The Doctor.
During the events of Hellsing: The Dawn, the researchers were stationed at a research facility in Warsaw that was provided by the Nazis. The Major gave them permission to study on She in order to advance their research in creating an army of Ghouls. They performed inhuman experiments on either the locals or invading Soviet forces and through their cruel experiments, they have successfully created the ghoul army that could turn the tides on the war.
On September, 1944, Arthur Hellsing sent Walter C. Dornez and Alucard to destroy the facility, they managed to kill all the researchers along with their creations, however Doc was still alive along with the remaining high rank Nazi officials who were involved in the project and would later continue their research and succeeded in creating a battalion of 1,000 Nazi vampires.
- They are based on existing occult nazi groups such as Thule society, Vril society and Ahnenerbe.