1970

The X-Men: 

Cyclops/Scott Summers

Iceman/Bobby Drake

Beast/Hank McCoy

Angel/Warren Worthington III

Marvel Girl/Jean Grey

Professor X/Charles Xavier

Allies:

Polaris

Havok
Changeling

Foes:

Sunfire [flight, plasma blasts, infrared vision, immunity to radiation]

Z’nox

The Hulk

A Japanese mutant; Shiro Yoshida, also known as Sunfire, attacks human Americans under the believe he was given special powers to avenge all the people who died when the atomic bomb fell in Hiroshima or after being exposed to radiation like his mother. He later changes his mind thanks to his father, who dies because of his fault. An alien race from the Andromeda Galaxy dedicated to enslavement called Z’nox, created a gravity transformer drive strong enough to transport their entire planet anywhere in the cosmos, choosing Earth as their target. Whenever they accomplish that, Earth would suffer terrible natural disasters after the balance of gravity becomes altered when the two planets get near to each other. To prevent this from happening, the X-Men join Havok and Polaris in a plan designed by Professor X himself, who has been alive all this time, but it was kept secret. Months before their battle against Grotesk, Xavier found clues about the Z’nox invasion, so he wanted to elaborate a plan without interruptions. At the time, Changeling, who had 6 months to live, approached to him and asks one last task to redeem himself and doing a good deed before dying, so he took Xavier’s shape to replace him in the battle against Grotesk and fake his death. Xavier links the compassionate minds of the world, funneled through Jean Grey, and blasts them through the optic beams of Cyclops towards the Z’nox.  Unable to handle the “mental corrosion” of this attack, the Z’nox reversed their planet’s course and left the solar system. After this, Xavier falls into a coma state from which he recovers thanks to a Gamma-ray powered device capable of curing mental exhaustion that belongs to Bruce Banner. They fight the Hulk on a rampage before that.

Side Note: Between issues 66 and 67, there was a considerable gap of several months without publishing anything new, followed by a long period with only reprints of early issues. Issue 67 would be the annoying start of a long reprint era, until issue 94 in 1975, where the story continues. “X-Men: The Hidden Years” series, published in years to come (1999-2001), tried to fill in the team’s chronology during the early 1970’s, but it was cancelled with issue # 22. The comic "Professor Xavier and the X-Men" tried also to re-tell the story from the begining (1995-1997), but it was financially unsuccessful too, with all the books being cancelled by issue #18.