Today marks the golden birthday of two classic Marvel teams — the X-Men and the Avengers, both of whom made their comics debut on September 10, 1963, drawn by Jack Kirby and scripted by Stan Lee. X-Men #1 introduced the "strangest superheroes of them all" — Cyclops, Marvel Girl, Beast, Angel, and Iceman, five mutant teens fighting to protect a world that hated and feared them — as well as Magneto, who would become one of their most iconic villains. The series was cancelled in 1970, 66 issues in, but relaunched in 1975 with Len Wein and Dave Cockrum's Giant-Size X-Men #1. Shortly after, writer Chris Claremont took up the reins of X-Men, which he penned through 17 years and a plethora of title changes and relaunches, including 1991's X-Men #1, which remains the best-selling comic book of all time. The Avengers #1 picked from a pool of existing heroes Lee and Kirby had created the previous year: Iron Man, the Incredible Hulk, Thor, Ant-Man, and the Wasp (Captain America, who had been around since 1941, was introduced in Avengers #4, when the team found the time-displaced super-soldier frozen in arctic ice). Since then, they've run with a rotating roster of the Marvel Universe's heaviest hitters — more than 100 heroes have served as active or honorary Avengers — and, like the X-Men, spawned a small army's worth of spin-off teams and titles. (Both teams, of course, have also launched their own powerhouse movie franchises, too.) Check out some of the iconic comics from both teams above, then stay tuned for the rest of the week, as WIRED celebrates the X-Men and Avengers' anniversary with in-depth looks at the history and iconic stories of both series. Above image from Avengers vs. X-Men #1. Art by Jim Cheung colored by Laura Martin, altered by Rachel Edidin

Avengers #1. Art by Jack Kirby

Avengers #4 introduced Captain America to the team. Art by Jack Kirby

X-Men #1. Art by Jack Kirby

Giant-Size X-Men #1. Art by Dave Cockrum