Do aliens really exist?

In Scientology doctrine, Xenu (also Xemu) is an alien ruler of the "Galactic Confederacy" who, 75 million years ago, brought billions of aliens to Earth in DC-8-like spacecraft, stacked them around volcanoes and blew them up with hydrogen bombs. Their souls then clustered together and stuck to the bodies of the living, and continue to wreak chaos and havoc today.