Randall Darby (also known as Shocker) was discovered and recruited by Magneto to become a member of the Brotherhood of Evil Mutants under the code-name of Shocker. After being abandoned by Magneto, this team reorganized as the Mutant Force. As the Mutant Force, they acted as lackeys for the Mandrill and later the Secret Empire.
When the United States passed the Mutant Registration Act, the Mutant Force renamed themselves the Resistants and took new code-names, Darby became known as Paralyzer. Their anti-registration protests was cut short by a clash with John Walker, the then current Captain America. Later, the Resistants reverted to their Mutant Force identities and costumes. Their next clash was with the New Warriors.
Paralyzer later battled Spider-Man, subduing him with a lucky blow. Spider-Man later teamed up with several members of the Midnight Sons who were investigating the activities of a more demonic Spidey-duplicate. While pursuing this creature, the heroes discovered and stopped the Paralyzer's plan to recreate Zzzax.
After the Sentinels destroyed Genosha, Paralyzer, again called the Shocker, helped Toad and other mutants create a statue of Genosha's former ruler Magneto. Unus became the leader of the group.
Shocker was seen during a meeting of Unus' people, after Unus himself was swallowed by Freakshow, one of the other mutants on the island. Their group was not sure if they would take Unus back if, in fact, he had survived. He did return, prompting Shocker and the others into attacking him in order to prove he still had the skills.
Shocker lost his powers during M-Day and the energies that he used to control were then drawn to The Collective.