Saitama (サイタマ) is the main protagonist of One-Punch Man and the most powerful hero alive. Saitama faces a self-imposed existential crisis, as he is now too powerful to gain any thrill from his deeds.
He is currently registered with the Hero Association as a B-Class Rank 7 professional hero and is tasked to defend Z-City against Mysterious Beings. Under the Hero Association, he is given the name Caped Baldy (ハゲマント).
Powers and Stats
Tier: Unknown, At least High 6-A, Likely 5-B, Possibly far, far Higher
Name: Saitama, Caped Baldy, Sensei (By Genos)
Origin: One-Punch Man
Attack Potency: Unknown (Has never used his full power at any point), At least Multi-Continent level (Overpowered Boros, who had the power to destroy the entire surface of the Earth, his punch created this much damage), Likely Planet level (An official databook states the Boros is capable of destroying the Earth), Likely far Higher (Boros was defeated casually, as in, entirely without effort and with the typical bored Saitama)
Speed: At least Sub-Relativistic (Managed to casually jump from Earth to the Moon and back again), Likely far Higher
Striking Strength: Unknown, Likely Class NJ to Class XJ, Possibly Class XKJ, Likely far Higher
Durability: Unknown, At least Multi-Continent level to Planet level, Likely far Higher (Survives every onslaught Boros can offer until he simply accepts that he cannot possibly harm Saitama in any way shape or form)
Stamina: Likely Superhuman
Standard Equipment: None
Intelligence: Can be easily distracted, lacks academic knowledge and has no martial art training
Weaknesses: Tends not to use his full power in fights, has no martial art training, can't breathe in space, he can, however, hold his breath for some time.
Note: Saitama tends to beat his opponents with no effort at all, and has not shown his full potential in the series with this said he could most likely be even stronger than how we make him out to be.