Origin
Michael Keane’s brother, John Keane, was the super-villain known as Tumbler. When John was assassinated by Moonstone in a bid to frame Captain America for his murder, Michael discovered that his brother had taken out a million dollar life insurance policy with the Guardian Life Insurance Company. Michael tried to collect on the policy but the Guardian Company refused to pay since John was killed while engaged in an illegal act. Michael tried to explain that his brother was being used by the Secret Empire but the Guardian Company would still not honor the policy. Michael trained hard and took his brother’s identity as the new Tumbler.
Creation
Tumbler was created by Bill Mantlo and Herb Trimpe and first appeared in Captain America #291. He is a legacy character based on the original Tumbler created by Stan Lee and Jack Kirby.
Character Evolution
Tumbler was introduced in a fill-in issue of Captain America and for the issue became an ally to the titular character. Despite plenty of mail in subsequent issues wishing to see the character again, Tumbler never did reappear.
Alternate Tumbler
Tumbler (Hobgoblin Franchisee)
An unknown individual that bought the name and costume rights from the Hobgoblin.