Sol Empire
The Sol Empire is a powerful intergalactic empire centered around Earth, but which exists in an alternate dimension. It is ruled by Ilik and controls roughly half of the Milky Way in the alternate dimension in which it exists. The only reason it doesn't control the entire galaxy is due to the empire's inability to defeat the last of The Nine Ancient Races who have survived the war despite Ilik's constant attempts to defeat what remains of them. This inability to push his war any further is due to his forces being already overstretched, which thus blocks them from pushing deeper into enemy territory. Once pushed back against by a superior force, the overextended empire forces crumble, opening the way to attack Earth, and defeat Ilik, after which the empire crumbles, and ceases to be a threat to the galaxy.