King is an S-Class hero rank 7, and known as The Strongest Man on Earth by public in "One Punch Man". He is a tall, lean built man, with three straight scar over his left eye and with sunken cheeks and a defined jawline. He first appear in Chapter 29 in the manga and episode 1 as a cameo but full appearance in episode 10.
What makes King unique is that he is the weakest hero in S-Class hero if not the entire Hero Association in "One Punch Man". Even though he is known as the Strongest Man on Earth, the reason for this title is due to mistaken Identity. King always present where a Mysterious Being is being killed with just one punch by Saitama, King takes the credits on all Saitama's achivements, that is the reason why the people and the hero association thought and dubbed him as the Strongest Man as they though he beat those Mysterious Being with only One Punch.
Even though he's weak and fake, Many Mysterious Beings in "One Punch Man" are still afraid of him, and this is because of his intimidating looks and the ability called "King's Engine" which is the sound of loudness and fast heartbeat of King from fear and anxiety. King's Engine is mistakenly claim by others to be a sound when King readies for battle and if he is serious.
During the Monster Association arc in "One Punch Man", even a Dragon level mysterious beings are being intimidated by King. When those monster are battling with the other S-Class heroes, they are worried they might get attacked by King who is just standing and watching the fight. Even when King is running away, they though that the reason he run away is to put those mysterious being in a trap.
A Mysterious being called Evil Natural Water is being attracted to powerful beings. But some of the Dragon level Mysterious Being in "One Punch Man" notice that he is not reacting to King at all thinking that even the mindless creature is scared to King. The truth is, Evil Natural Water don't feel any strong presence from King.
That intimidation of King is giving him some advantage. We will just need to wait for "One Punch Man" Season 2 to be released to see him in action. King will surely give us a lot of intimidation and laughter.