10 Most Interesting X-Men You've Never Heard Of

10. Sage

Sage was first introduced in the 1980's as Tessa, a member of the Hellfire Club and personal assistant to Sebastian Shaw. However, it was later revealed that she was really a spy, working for Professor X.

Tessa had met Charles Xavier years ago when she helped him get to a hospital after a battle with the evil alien Lucifer (some bad guys aren't exactly subtle) left him crippled. Tessa was one of Charles' first recruits for the X-Men but, instead of adding her to the team, he sent her to spy on the Hellfire Club, suspecting they could be a problem in the future.

After her cover was blown, Sage joined the X-Men proper. She helped a team led by Storm (the abysmally named X-treme X-Men) find diaries written by the prophetic mutant Destiny before leaving to help Sunspot take over the Hellfire Club. Since then she's appeared on the spin-off team Excalibur and travelled to alternate realities with the Exiles and a new team of X-treme X-Men (some sadist decided we can't just let that name die). She hasn't been seen since that series was cancelled.

Part of what might make writer's reluctant to use Sage is how vague and arbitrarily thrown together her powers are. Apart from telepathy, she has "superhuman mental processing" which usually translates to "is good at computers" and can "jumpstart" other mutant's powers, which pretty much gives them the ability to resolve whatever plot they're in.