Orochi

Orochi is the Monster King and leader of the Monster Association — an enormously powerful monster created through the forced evolution process devised by Psykos. He possesses a massive serpentine body with multiple dragon heads and can absorb other monsters to grow even stronger. Orochi can manipulate the Earth's energy through Gaia Cannon and was powerful enough to briefly impress Saitama. After being seemingly killed, he merged with the Earth's core and was used as a vessel by the entity God.