Genos (ジェノス, Jenosu) is the deuteragonist of One-Punch Man. He is a 19-year-old cyborg and the disciple of Saitama. He is always aiming to become more powerful and he fights for justice. Under the Hero Association, he is given the name Demon Cyborg (鬼サイボーグ, Oni Saibōgu) and is currently S-Class Rank 14.

Genos is a mechanical cyborg of average human height. His face and ears look like that of a normal human, made of artificial skin material, and his eyes have black sclera with yellow irises. He has spiky blond hair and his eyebrows are blond (brown in the anime). He also has pierced ears. Genos’s wardrobe consists of street clothes with all of his upper-body attire being sleeveless as to allow his arms to transform without hassle. He has many different sets of arms, with varying abilities and strengths. Notable examples of his various “arms” are those he used in his sparring match against Saitama and the arms he equipped to combat the meteor. Sometimes the arm sets he uses create a metal framing around his face, like when utilizing Arms Mode and in his Monster Association Arc Upgrade.