One cited deathOne Punch Man
Does this death move the ranking?

Confirms the ladder

The higher-ranked entity killed the lower-ranked one. Record and ladder agree.

Tatsumaki vs Monster King Orochi

The killerTatsumakiOne Punch Man · rank 5
4 places
The victimMonster King OrochiOne Punch Man · rank 9

The one death here that corrects a false impression left by the man at the top. The monster king had already been blown to pieces underground and had already come back, drinking whatever crawled past until the pieces held, because the heart went on beating. Twenty-nine chapters later an esper takes that body apart and wrecks that organ specifically, and it stays destroyed. The ladder is unmoved — killer above victim, as expected — but the entry it corrects is the one people quote, which is that the Monster Association's leader was a one-punch job. He was not. He was a one-punch job with an unfinished ending, and somebody else finished it.

The connecting record

shownOne Punch Man

Tatsumaki killed Monster King Orochi in One Punch Man.

What each of them is ranked on

The killer · Tatsumaki · rank 5

Tornado of Terror

WebcomicMangacomiccontested

Pulled the Monster Association's headquarters bodily out of the ground while shielding the heroes still inside it, then finished Monster King Orochi — Psykos had split off the fusion and fled by then — by shredding the body and destroying the heart, the organ Saitama's punch had left beating. Almost nothing else here moves that much mass without touching it.

  • shownOne Punch Man · ch. 134

    Raises the whole Monster Association headquarters out of the earth while shielding several heroes inside the facility.

  • shownOne Punch Man · ch. 137, pp. 6-8

    Pulls meteor-sized rock formations out of the ocean and throws them at the fusion.

  • shownOne Punch Man · ch. 138, pp. 11-13

    Stops one of the fusion's energy attacks dead in the air and tosses it aside.

All 8 citations
  • shownOne Punch Man · ch. 143

    Psykos splits away from Orochi and escapes before the killing blow lands.

  • shownOne Punch Man · ch. 144

    Shreds Orochi's body and destroys his heart, which is what ends him.

  • shownOne Punch Man · ch. 34, pp. 21-25

    Halts the bombardment from Boros's ship and sends it back at the ship.

  • shownOne Punch Man · ch. 126

    Locates Psykos fifteen hundred metres underground and drags her up out of it.

  • shownOne Punch Man · webcomic ch. 102, p. 12

    Tries to throw Saitama into space in the webcomic, gets him a few feet off the ground, and says he is heavy.

Tatsumaki on the One Punch Man ladder

The victim · Monster King Orochi · rank 9

Mangacomic

Head of the Monster Association and the thing its sacrifices were feeding. Blown apart underground and still conscious afterwards, he dragged himself back together out of other monsters' blood, tried to swallow the woman who had made him, and came out of that merger holding a share of "God's" power. Twenty-nine chapters passed between the punch and the body finally stopping.

  • statedOne Punch Man · ch. 74, p. 10

    Gouketsu calls him the strongest monster on Earth.

  • statedOne Punch Man · ch. 114, p. 13

    Psykos says she cannot gauge his power and calls him a real monster.

  • statedOne Punch Man · ch. 115, p. 7

    Already knowing Saitama beat Overgrown Rover, and sensing the pressure off him, works out that he also beat Gouketsu and Elder Centipede.

All 8 citations
  • shownOne Punch Man · ch. 131

    Survives being blown apart by Saitama and regenerates by absorbing the blood of other monsters.

  • shownOne Punch Man · ch. 132, pp. 9-12

    Attempts to absorb Psykos and the two end up sharing one mutated body.

  • statedOne Punch Man · ch. 136, pp. 16-20

    "God" appears during the merger and adds power to the fusion.

  • shownOne Punch Man · ch. 136, pp. 7-13

    The fusion's attack cuts through the Earth's surface and lifts a severed disk of oceanic crust, seawater and the sky above it.

  • shownOne Punch Man · ch. 160, pp. 44-45

    What is left of the body is used as a sacrifice to resurrect Sage Centipede.

Monster King Orochi on the One Punch Man ladder

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.