Captain Boomerang

Captain Boomerang is a reoccurring enemy of the Flash and member of his Rogues Gallery. He’s known for his personally made Boomerangs which have varying abilities, all with deadly affect.

Early History
Captain Boomerang first appears in the GCW continuity as working for the Suicide Squad, and trying to subdue the escaped Deadshot, who’s attempting to kill Amanda Waller—the then Leader of the Suicide Squad.

This is the first and currently only reference to Captain Boomerang being apart of and working for the Suicide Squad. His immediate history after this event is unknown, and he is not brought up again until his appearance in Task Force X.

Task Force X
Captain Boomerang next appears as joining (Forcibly) the group Task Force X; which appears as very similar group to the Suicide Squad. Harkness is joined by various other villains, including Clock King, Plastique, Coco, and Firefly; the latter of whom was quickly removed from the group after disobeying rules and replaced by Mirror Master.

Harkness was very angry that he’d been placed into Task Force X, most likely because he was not told anything until he was already initiated (By having a bomb secretly planted at the top of his spinal cord), like the other members of the group. Like the fellow members he was surprised to learn the group’s first mission was to assassinate then President Lex Luthor.