Captain Boomerang has created many trick boomerangs, including exploding boomerangs, sonic boomerangs, grappling hook boomerangs, etc. Harkness has also created several rocket-assisted boomerang-missiles, capable of launching his foes into outer space.
Thrown Weapons (Boomerangs) * Desert Survival
Martial Arts B * Confidence Games
The Secret Society of Super-Villains * The Flash's Rogues Gallery
Arriving in Central City to begin a new phase of his criminal career, Australian outlaw "Digger" Harkness chanced to read a "Help Wanted" ad from the Wiggins Game Company. It seemed company owner W.W. Wiggins was determined to make the humble boomerang the next national toy craze, and was searching for a boomerang expert to serve as the company's symbol for the campaign. Having mastered the instrument during his years hiding from the law in the Australian Outback, Harkness applied for the job and got it.
Given a specially designed uniform and the trade name Captain Boomerang by Wiggins himself, Harkness set about promoting the company's product while secretly using special boomerangs of his own design to commit daring robberies.
Ultimately, Harkness was confronted in the act of committing a jewel robbery by the Flash and, after a heated battle, was defeated and imprisoned for his crimes.
In the ensuing years, Captain Boomerang has become one of the Flash's most persistent foes, battling the Speedster again and again.