20 Most Powerful X-Men Villains Of All Time

20. The Danger Room

Joss Whedon and John Cassaday's Astonishing X-Men run was a breath of fresh air which also riffed on a lot of classic themes, characters and concepts for the mutant team. Claremont fan Whedon reintroduced Kitty Pryde to the Xavier School, and made it...well, like a school again. They also reinvented the Danger Room.

It was revealed the mechanical death-trap used to put the X-Men through their paces was actually a sentient intelligence Professor X had trapped and forced to become a deadly, high-tech gym. All of a sudden it managed to break free of its restraints and went loco, beating Emma Frost to a pulp and convincing a student to commit suicide.

Along with being scary because, well, the Danger Room is a familiar concept and seeing it made into a lady-shaped robot with all its usual lasers and circular saws directly attacking people is messed up. Ultimately it couldn't over-ride its programming and actually kill anyone directly, but still. It was essentially a Terminator molten lava didn't work on.