John Robert Keane became a costume criminal acrobat named the Tumbler. He wanted to test himself against Captain America but was defeated. Sometime later he was hired by a Secret Empire member named Quentin Harderman to play an instrumental role in a plot to discredit Captain America. John Keane in his civilian clothing engaged Captain America in an exhibit hall with many witnesses. During the fight, the first Moonstone assassinated the Tumbler with a micro laser beam setting Captain America up for murder.
The Tumbler was created by Stan Lee and Jack Kirby in 1966 and first appeared in Tales Of Suspense #83.
Powers and Abilities
The Tumbler does not have any superhuman abilities but is in peak physical conditioning. He is a skilled acrobatic with extraordinary agility and reflexes. He can leap great distances and is very good in hand-to-hand combat.