Daishinkan Darom (High Priest Darom)
The senior of the three Gorgom Priests was the most wise and knowledgeable. Responsible in the surgery which transformed Kotaro and Nobuhiko into Black Sun and Shadow Moon respectively. Usually he was the one who tried to calm the other priests down whenever they had an argument with Birugenia. Darom had the ability to mutate his hand into claws in order to perform operations. He also had the power to manipulate people, tossing them around in midair by just pointing at them. After losing the power of the "Stone of Heaven" within him to revive Shadow Moon, Darom is reborn as Grand Mutant Darom, a trilobite-like creature. Following Baraom and Bishium's death, Darom attacked the ex-Shonen Warriors until Kotaro arrives and fights Darom until Shadow Moon arrives, killing Black and sending Darom to find his corpse to obtain the Kingstone. Darom finds Whale Mutant's cave and learns that Kotaro had been revived. Darom and Bat Mutant then had some Gorgom worshippers capture Whale Mutant as bait for Kotaro. After Black threw himself in front of Whale Mutant, he then used his King Stone Flash to deflect Darom's attack before killing him with the Rider Kick.

Daishinkan Baraom (High Priest Baraom)
He is the tallest High Priest having an upset green face, Baraom can fire deadly laser beams from his robotic fingers. He is very hot-tempered and easily irritated by Birugenia's presence. He is usually in charge of the deployment of Gorgom's Mutants. After losing his powers from the "Stone of Ocean" within him to revive Shadow Moon, Baraom is reborn as Grand Mutant Baraom, a creature resembling a saber-toothed tiger. He wielded tusk-shaped weapons along with his natural abilities. After Bishium's destruction, Baraom trained himself to avenge her and even got the Whale Mutant to help him. Baraom started to use his super-speed to overwhelm Black before Whale Mutant betrayed him. Baraom mentions that Shadow Moon will finish him off before being killed by Black.

Daishinkan Bishium (High Priestess Bishium)
She can discharge laser beams from her eyes. After losing her powers from the "Stone of Earth" within her to revive Shadow Moon, Bishium is reborn as Grand Mutant Bishium, a white-haired purple rhamphorhynchus, pterosaur-like creature. In this form, she still has her usually powers and she can spin around to create twisters. Bishium became overconfident of herself and even tried to convince Shadow Moon that her plans could finally defeat Kamen Rider Black, ignoring advices from her good allies, Darom and Baraom. When it came to the final confrontation with Black, she tried to get the King Stone from Kotaro by taking control of the mothers and capturing Kyoko. In the conflict, Bishium held Black so that Shadow Moon can shoot a beam that will rip out Kotaro's King Stone. It failed as Bishium is destroyed by that beam.

Ken Sei Birugenia (Sword Saint Birugenia)
Birugenia, Gorgom's warrior, made his first appearance in episode 18. He was born 30,000 years ago on a day of a solar eclipse, just like Kotaro & Nobuhiko. However, a Kingstone was never given to him because the Creation King didn't favor him and therefore he could not become the next Creation King. This made him angrily trying to revolt against him and resulted with the Creation King sealing him in a coffin. The Creation King ordered the three High Priests to release Birugenia after they kept failing to retrieve the Kingstone from Kotaro. He was both a pain for Kamen Rider Black as well as to Gorgom.

Birugenia always wanted to be the one to kill Kamen Rider Black, thus kept interfering in the High Priests' plans. In episode 22, Birugenia went back to his old white face form from 30,000 years ago, making him more powerful and more arrogant. In episode 25, he had Yoichi Daimon's pupil Egami create the Hellshooter: an equivalent to Road Sector. He used it to challenge Kamen Rider Black and Road Sector only for the Hellshooter to be destroyed. During Gorgom's latest attempt to use Kyoko's lifeforce to awaken Shadow Moon, Bilgenia stole the Satan Saber and attacked the High Priests before running off with Kyoko and going after Black to take his King Stone for himself. However, Kotaro and Kyoko manage to hide from Bilgenia as he decides to attack the city to flush Kotaro out by using his Satan Cross to cause anarchy with a group of young men. Arriving to the scene, Black battles Bilgenia until Shadow Moon finally awakens and he claims the Satan Saber, forcing Bilgenia to retreat as his influence wears off. Returning to the Gorgom shrine, Bilgenia fought Shadow Moon who disarmed and then killed him.

Mara & Kara
Mara & Kara were created by Shadow Moon and are higher ranks than the Three High Priests. They first appeared in episode 38. Both handmaidens died during the collapse of Gorgom's base. Mara was the silver handmaiden mutant and Kara was the golden handmaiden mutant.
Human Members
Gorgom allows any humans to join them. They were lured into the syndicate as they found Gorgom's offers interesting. These humans were willing to become Gorgom's monsters which could live for up till 5,000 years.
Soichiro Akizuki
Soichiro Akizuki is an archaeologist and friend of Kotaro's father, Soichiro joined Gorgom to financially support his archaeological projects. He was assassinated by Gorgom for disobeying their orders, for he realized that they were an organization of evil.
Ryuzaburo Sakata
A politician who used his political and non-political connections in performing tasks that Gorgom could not expose themselves into, such as kidnapping or assassination. He was responsible for leading a pro-Gorgom political party known as the EP Party with Omiya.
Koichi Omiya
The head of Omiya Konzern, he used his business connections in finance Gorgom's criminal and terrorist activities. He is one of the EP Party's leaders with Sakata.
Professor Hideomi Kuromatsu
A scientist, Nobel Peace Prize winner and Tohto University professor. He was Gorgom's chief scientist in converting humans (willing or not) into various mutants. He also has interchangeable hands for him to experiment on said humans. He uses his Tohto University job as a sanctuary for Gorgom's mutants and as a laboratory for conducting conversions for humans and for Mutant-related experiments. He was later killed off-screen for his failure to eliminate Black and Birugenia briefly assumed his appearance.
Yukari Tsukikage
One of Japan's most famous actresses, she was assassinated by the Leopard Mutant when she unintentionally mentioned that Kotaro and Nobuhiko were becoming Century Kings on their 19th birthday party.
Shigeru Sugiyama
Believed to be a former JGSDF (Japanese Ground Self-Defense Forces) soldier, he uses his training to raise the Gorgom Destruction Team as a commando task force for Gorgom before Kotaro forced him to come to his senses.
The Creation King
The ultimate leader of Gorgom was unseen for the entire series. Supposedly it is the most powerful being that had been living for the past 50,000 years. The true face of the Creation King was a giant floating heart was first seen in episode 50. It communicated with the Priests and the two Century Kings via telepathy. It also had monstrous strength that could destroy the entire universe.
Series:  Kamen Rider Black