Introduced in: Ultimate Spider-man #1 (2000)
It was the start of a new millennium. With the release of the first Sam Raimi Spider-man movie, Marvel was looking to bring in new readers who they hoped would begin reading comic after the movies’ release. Since they didn’t want new readers to be bogged down by decades of continuity, Marvel decided to release a retelling of Spider-man’s origins. Thus, Ultimate Spider-man was launched alongside the movie, which was a quite different take of the Spider-man mythos. While initially a mini-series, the sales of this book allowed Marvel to continue the story of this universe. As it went on, they began adding other series to the line, with Avengers, X-men and Fantastic Four all receive new origins in this universe. This would last for many years until the imprint was eventually closed.
This universe would also be the inspiration for many movies, including the first Avengers movie. Not only that but it introduced many characters that would eventually become mainstay of the Prime Universe, particularly Miles Morales, who would be brought into the Prime Universe.