Crisis on Infinite Earths was a twelve-issue miniseries from DC Comics1 published from 1985 to 1986. It was written by Marv Wolfman, and pencilled by George Pérez2.
There are many versions of the Earth, each with their own histories. The superheroes of Earth One made contact with their counterparts on Earth Two an indeterminate time ago. In what almost seemed to have become an annual tradition, Earth One’s Justice League periodically teamed up with Earth Two’s Justice Society to deal with crises affecting both worlds.
Now there is a crisis affecting not just Earth One, and Earth Two, but all the worlds.