Lavos

Lavos is an alien parasite that is so powerful, it's mere existence creates time gates everywhere.

Story
Lavos felt on Earth in the year 65000000 B.C., quickly digging it's way through Earth's subsoil. There he resided in order to store power, until in 1999 A.D., he raised to the suface and released all of his power, destroying the planet completely. Then he started spawning his children, who would continue the cycle.

About Lavos
Basically Lavos' lifecycle is falling on a planet, then he influences the evolution of all species on the planet, in order to cultivate their DNA to raise itself. After some time, he unleashes all of his power, destroying the planet and start breeding his spawns to continue the cycle in others planets.

He was summoned twice in time. First in 12000 B.C. by Queen Zeal, who was blinded by Lavos's amazing power. This made Lavos unleash a bit of his energy, enough to destroy the Kingdom of Zeal completely. He was summoned later in 600 A.D. by Magus, who wanted to take revenge on Lavos for destroying the Kingdom of zeal and making him time-travel to that time.