The connecting record
shownOne Punch Man
Saitama killed Deep Sea King in One Punch Man.
One punch, delivered after the thing had been through a shelter's worth of heroes, and the shockwave stopped the rain.
What each of them is ranked on
The killer · Saitama · rank 1
Caped Baldy — Hero Association register
Aced every physical test at the certification exam and scored 71 out of a pass mark of 70, which put him at the bottom of the lowest class in the organisation. Punched apart the meteor falling on Z-City, killed the Deep Sea King in one blow in front of the heroes it had already gone through, and met a beam aimed at the Earth's surface with a Serious Punch whose shockwave parted cloud cover across the planet.
statedOne Punch Man · ch. 16, pp. 1-8
The certification exam awards him 71 points against a pass mark of 70 and a C-class designation.
shownOne Punch Man · ch. 16, pp. 1-8
Takes the physical tests at the exam centre in front of examiners and rival candidates.
statedOne Punch Man · ch. 17
Genos, reading the registry, says the two of them have been placed at the lowest rank of S-class and of C-class respectively.
All 11 citations
statedOne Punch Man · ch. 21, pp. 1-4
Genos tells him he has been moved from C-class rank 388 to rank 342.
shownOne Punch Man · ch. 21
Punches through the meteor falling on Z-City and walks away.
shownOne Punch Man · ch. 28
Kills the Deep Sea King with a single blow.
shownOne Punch Man · ch. 36
Repels Boros's Collapsing Star Roaring Cannon with a Serious Punch.
shownOne Punch Man · ch. 36, pp. 54-57 & 62-63
The shockwave off that punch parts the cloud cover across the whole planet.
statedOne Punch Man · ch. 36, pp. 68-69
Boros tells him he had strength to spare and was still holding back.
statedOne Punch Man · ch. 177, p. 37
Is promoted to A-class rank 39 after the Monster Association incident.
statedOne Punch Man · webcomic ch. 96, p. 16
The webcomic gives the same A-class rank 39 placement.
The victim · Deep Sea King · rank 11
One afternoon, and in no order the register would recognise: Stinger and Lightning Max out of A-class, then the S-class Puri-Puri Prisoner, then Sonic, who is on no register at all, then the four heroes at the shelter door, then Genos out of S-class again, and last of all the C-class Mumen Rider, beaten down twice and still the last man there to stand up. The story stops to draw every one of them losing. That sequence, rather than the single punch that ended it, is the clearest measure on this ladder of what the middle of the Association is actually worth.
shownOne Punch Man · ch. 23
Comes out of the sea and downs the hero Stinger with one punch.
shownOne Punch Man · ch. 24
Punches the A-class hero Lightning Max out of a building and into the street.
shownOne Punch Man · ch. 25
Beats the S-class hero Puri-Puri Prisoner with a combination ending in a kick that sends him through a building.
All 8 citations
shownOne Punch Man · ch. 25
Returns to full form in the rain and chases Sonic off the rooftops, leaving him only his clothes.
shownOne Punch Man · ch. 26
Puts down Jet Nice Guy, Bunbun Man, All Back-Man and Sneck at the evacuation shelter.
shownOne Punch Man · ch. 26-27
Tears Genos's arm off, spits acid at an evacuating child, and puts the cyborg through a wall.
shownOne Punch Man · ch. 27
Beats Mumen Rider down twice in front of the shelter and throws him into Saitama's arms.
statedOne Punch Man · ch. 28, p. 3
Calls himself the pinnacle of a pyramid containing every organism on Earth.
What this does not settle
One death in one work. It is the only place the record puts these two in the same room, and it is evidence about that meeting and nothing wider — not a general matchup, not a rematch, and not a ranking of its own.
The ladder above it is argued from everything either of them has been shown doing; this page is argued from one citation.
Where the two disagree, the disagreement is the point, and it stays visible rather than being resolved by whichever of them happens to be on this page.