Elagabalus was a god worshipped by some people long, long time ago. People believed he had power over the sun, moon, and stars. They thought he could control the weather and make good things happen for them.
Some people believe that Elagabalus was just a made-up god that someone started worshipping. But others think he might have been a real person long ago who people thought was very powerful and important. His name means something like "God of the Mountain."
Elagabalus was worshipped in a temple in a city called Emesa, which is in what we now call Syria. People would bring offerings to the temple to make Elagabalus happy and ask for his help. They believed he would protect them from harm and make their lives better.