Xenu isn’t really a correlate to Satan. Satan of the Old Testament was an agent of God who tested human beings’ commitments to God, effectively by torturing them in ever-crueller ways to determine how much any individual could take before he (shes didn’t matter in those stories; they were property) condemned God. Later, Satan was conflated with Lucifer, who had been God’s favorite angel until God changed loyalties on a whim and Lucifer asked why he had been rejected after being a faithful servant. Lucifer was punished for questioning God by being cast out of heaven and down to hell. This Satan-Lucifer hybrid was effectively a version of a pagan trickster deity, and John Milton capably redefined the character in Paradise Lost as a master manipulator and deceiver who resented human beings for taking his place as God’s favorite creation.
Xenu is more of a Superman villain type. He was the dictator of a galaxy that became overpopulated and so to solve that problem, he banished some of his people to Earth, imprisoned them inside volcanoes and then blew up the volcanoes with nuclear bombs. The spirits of those beings evolved into human beings, say the Scientologists, and they infect us as “soul fleas” that Scientologists believe their church has the power to eradicate.
When a Scientologist “goes clear,” that means that their mind and bodies have been cleared of soul fleas or “thetans.” Tom Cruise railed against Brooke Shields for taking antidepressants because Scientologists believe that psychology and psychiatry are evil practices developed by evil beings to keep the soul fleas inside our spirits.
So not exactly the same as Satan. Much more like a modern comic book mythology involving aliens and good-versus-evil supervillains, plus Tom Cruise in elevator shoes.
“75,000,000 years ago, Xenu headed the Galactic Federation, which was an organization of 76 planets that had already existed for 20,000,000 years. The planets were suffering a tremendous problem with overpopulation. Xenu's draconian solution to the matter was to gather large numbers of people, kill them, freeze their thetans (souls), and transport the frozen thetans to Earth, which they called Teegeeack. The thetans were left in the vicinity of volcanoes, which were, in turn, destroyed in a series of nuclear explosions.
“Members of the Galactic Federation eventually rebelled against Xenu, fighting him for six years before he was finally captured and imprisoned on a planet that today is barren desert. Within the "mountain trap" on this unnamed world, Xenu still lives.”