King Drasil

Yggdrasil is the name of a computer program from Digimon. It is the primary ruler of the Digital World.

Digimon X-Evolution
When the Digital World began to become too overpopulated, Yggdrasil considered this to be a Digital Hazard since he can't handle this. Yggdrasil decides to initiate Project Ark by unleashing the X-Program to delete every Digimon except for a few selected ones. Those selected ones were moved to a new Digital World that Yggdrasil had created through three separate plans: Urd, Verdandi, and Skuld. When some Digimon started to develop new forms from the X-Program resulting in Digimon with the X-Antibody, Yggdrasil sent the Royal Knights to deal with them after they moved to the new Digital World. Yggdrasil began the second phase of Project Ark: the deletion and destruction of the Digital World and it's Digimon (both normal and those with the X-Antibody). Alphamon and Omnimon confronted Yggdrasil who just begun the second phase of Project Ark by unleashing the DexDorugremon upon the Digital World. Once Omnimon destroyed Yggdrasil, the Digital World was reborn to the way it was.

Digimon Savers
Suguru Daimon and his expedition were looking for Yggdrasil in order to ask it to let them bring back Ikuto Noguchi. However, they ran into Mercurimon and Suguru's expedition fled back to the Digital World while he faced Mercurimon. He told Mercurimon of his mission and left to seek Yggdrasil.