Earth 616 is the main universe where most x men comics take place.
Home to X men, Spiderman, Fantastic Four, the Avengers and more.
The 616 universe first appeared in Fantastic Four issue 1 by Stan Lee and Jack Kirby. This universe's version of the X men were also the first incarnation ever. This is by far the most iconic comic version of the team. The team in this universe is known for consistently changing.