Leech, often called Jimmy, is a mutant with involuntary powers, only activated in proximity to remove all effects of mutant genes, including physical mutations. For example, when Hank McCoy reached out to shake Jimmy's hand, his own hand lost its furry blue appearance; his mutation returned once he left Leech's presence.

Leech played a pivotal role as the source of a "cure" for the mutant gene. Magneto planned to kill Jimmy, who was being kept at Alcatraz Island, thus destroying the cure and preserving the mutant species. Magneto and his Brotherhood of Mutants attacked the facility, which was defended by federal troops as well as the X-Men.

Juggernaut was sent to find Jimmy and Kitty Pryde raced to save him. When Pryde discovered that she was unable to phase through walls while with Jimmy, she allowed Juggernaut to charge at them. She allowed Juggernaut to slam into the wall. Instead of breaking through, Jimmy's nullifying powers had removed his invulnerability knocking him unconscious.

Later, Jimmy was evacuated from Alcatraz Island with Pryde and Bobby Drake. He eventually became a member of Xavier's School and was well received by the new leader, Storm.


He could nullify the powers of every mutant who came near him, rendering them to normal while in his effect range.

Strength level

Normal human male

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