Which celestials head is Knowhere?

During the Secret Wars storyline, Knowhere is shown to be the Moon that orbits Battleworld. Its origin is that this Knowhere is the head of a Celestial that came to collect Battleworld but was slain in battle by God Emperor Doom and its head is still in orbit around Battleworld as a reminder of Doom’s power.

Who decapitated Knowhere Celestial?

Trivia. In the comics, Knull, the overlord of the Symbiote race, decapitated a Celestial’s head and as it eroded over a millennia; it was taken placed as a city known as Knowhere. Knowhere orbits in a binary system, around a black hole currently absorbing its twin star. Knowhere’s coordinates are M3RD 17H17211+2121224.