Source: wonderslist.com

4. Vulcan

Unclassifiable

That’s right, folks. The rest of the characters on this list are BEYOND OMEGA LEVEL.

Boy, if you thought Cyclops was kind of a boring character, wait until you meet his brother!! No, not Havok. Havok is cool.

You see, the Summers parents were abducted by aliens before they shoved their two children out of the plane to safety. Huh. S-a-f-e-t-y. Weird way to spell almost certain death, but to each his own. So, when The Summerses were abducted, Katherine Summers was pregnant with another child. The child, Gabriel Summers, was raised by the Shi'ar and sent back to earth.

When Krakoa the Living Island kidnapped the original X-Men, Professor Xavier recruited a new team of X-Men to go and save the original squad. Vulcan was recruited as part of the team – leader, in fact. The entire team was killed, only managing to save Cyclops before being decimated. Vulcan survived in secret, however, and was shot into space with the rest of Krakoa by the newly formed Uncanny X-Men. Years later, he returned to Earth, where he menaced the X-Men for some time.

Power Level: Described as Past Omega Level by Professor X. So that's pretty serious business.