Partner(s): Genos Saitama is the most powerful hero alive. Having apparently trained himself to superhuman condition, Saitama faces an existential crisis as he is now too powerful to gain any thrill from his heroic deeds. He is registered with the Heroes Association as a C-Class Superhero and is tasked to defend Z-City against Mysterious Beings. Saitama is usually deliberately drawn in a simpler style than other characters, with a very rounded head and only a simple mouth and eyes. When drawn in a more 'action-oriented' style with more detail, Saitama is revealed to have sharp features, dangerous looking eyes, and chiseled musculature. His costume is a plain yellow jumpsuit with a short zipper at the collar and a belt. The costume is finished out by an ensemble of red boots and gloves, and a white cape. For a superhero, Saitama is rather laid back. Because even the mightiest foes pose no challenge to him, he doesn't take his hero work very seriously. In spite of this, he is constantly searching for an opponent that can challenge him, since his superhero work is beginning to bore him because it's too easy. The combination of his attitude, unstoppable strength, and distinctively simple and 'unimpressive' appearance often cause his battles to become anticlimactic. Saitama will usually allow his opponents to rant about their motives and power up into their strongest forms before suddenly and nonchalantly obliterating them with one punch. (Source: One Punch-Man Wiki)

Spike Spiegel is a tall and lean 27-year-old bounty hunter born on Mars. The inspiration for Spike is found in martial artist Bruce Lee who uses the martial arts style of Jeet Kune Do as depicted in Session 8, "Waltz For Venus". He has fluffy, dark green hair (which is inspired by Yusaku Matsuda's) and reddish brown eyes, one of which is artificial and lighter than the other. He is usually dressed in a blue leisure suit, with a yellow shirt and Lupin III inspired boots. A flashback in Session 6 revealed it was his fully functioning right eye which was surgically replaced by the cybernetic one (although Spike himself may not have conscious recollection of the procedure since he claims to have lost his natural eye in an "accident"). One theory is that his natural eye may have been lost during the pre-series massacre in which he supposedly "died". The purpose of this cybernetic eye is never explicitly stated, though it apparently gives him exceptional hand-eye coordination - particularly with firearms (Spike's gun of choice is a Jericho 941, as seen throughout the series). In the first episode, when facing a bounty-head using Red Eye, Spike mocks him, calling his moves "too slow". At first, this seems like posturing on Spike's part, but even with his senses and reflexes accelerated to superhuman levels by the drug, the bounty cannot even touch Spike. A recurring device throughout the entire show is a closeup on Spike's fully-natural left eye before dissolving to a flashback of his life as part of the syndicate. As said by Spike himself in the last episode, his right eye "only sees the present" and his left eye "only sees the past." Spike often has a bent cigarette between his lips, sometimes despite rain or "No Smoking" signs.