Cyclops Mask, known as Hitotsume Kamen in Japanese, is a Masked Monster and a villain from the television series Himitsu Sentai Gorenger. This character serves as the fourth monster created by the Black Cross Army's general, Sun Mask, making him a significant threat during the series' early confrontations with the Gorenger team.

The primary mission of Cyclops Mask is to abduct children from across Japan. He operates from a secret island base where he subjects the captured youths to a brainwashing process. The goal of this scheme is to transform ordinary children into young soldiers for the Black Cross Army, referred to as young Zolders, who are visually distinguished by a large eye emblem on their uniforms instead of the standard Zolder goggles. This motivation highlights his role as a direct threat to the innocence of the next generation, serving the broader ambitions of the Black Cross organization.

In his role within the story, Cyclops Mask is the central antagonist of episode eighteen. His plan is set in motion when he attempts to kidnap a group of children. The Gorengers, Tsuyoshi and Kenji, initially intervene, but Cyclops Mask, with support from Sun Mask, manages to abduct Kenji and escape with several children. This event forces the other Gorengers to devise an infiltration strategy. Two members, Daita and Peggy, pretend to be brainwashed, allowing themselves to be captured to reach the monster's base. Once inside, they learn the details of his operation while maintaining their cover, eventually turning the tables on Cyclops Mask and freeing the captives.

Key relationships in this episode include Cyclops Mask's loyalty to his superior, Sun Mask, who supports the child abduction scheme. His primary antagonistic relationship is with the five Gorengers, particularly Kenji, who is captured, and Daita and Peggy, who successfully deceive him. The character does not undergo significant development, as he is a monster of the week who is defeated by the episode's end.

Notable abilities are central to Cyclops Mask's evil scheme. His most powerful weapon is a form of hypnosis generated by his single, glowing eye. This ability allows him to trap victims in a trance, forcing them to submit to his will and obey his commands. He can also use this hypnosis to place fake eyes onto children as a method of mind control. For physical combat, Cyclops Mask wields a spear, the butt of which contains a strangling string that can return to him when thrown. He is also capable of shooting ribbons from his eye and can swim. The Gorengers ultimately defeat him by exploiting a weakness in his eye. Aorenger shoots him in the eye, temporarily blinding him, before he is finished off by the team's combined Gorenger Storm attack.