777, also known as Three-Seven or Triple Seven, is a genetically engineered clone produced by bio-weapons experiments at the Dead Leaves lunar prison. He operates as a primary enforcer and guard under Warden Galactica's command. His physical design prioritizes bulk and raw power, establishing him as the physically dominant counterpart to the taller, leaner clone 666.

His cybernetic augmentations integrate an array of concealed firearms and weaponry deployed during combat and suppression duties. Preferring brute strength over finesse, he employs lethal finger-based attacks, poking holes through victims or dismembering them with flicks. Despite his role enforcing institutional control, he exhibits Ambiguously Christian behavior, frequently uttering brief prayers seeking divine forgiveness immediately before violent confrontations—a habit 666 criticizes as being "a little late for that."

During the mass prison break led by Retro and Pandy, 777 actively suppresses the uprising. He confronts Retro directly, utilizing both his integrated weaponry and physical strength. His combat style consistently relies on overwhelming force, including attempts to crush Retro's head while declaring, "God is waiting for you." His actions extend to executing inmates who violate regulations, notably impaling Dick Drill after Drill's attack lodges in his neck.

777 meets his end when Warden Galactica absorbs him and 666 into her own body during her transformation into a giant caterpillar entity, part of her deranged fairy tale reenactment in the final confrontation. This assimilation eliminates him as a distinct entity.