These lethal legends loomed large literally! Doctor-Seven and Doctor Clever had a knack for coming up with crazy schemes that thoroughly perplexed their heroic foes, while dressed in their best tuxedo's exuding an air of arrogance.
Doctor-Seven was a rival to Mark Merlin, an investigator into Earth-One's unknown. Eventually, he came upon the creation that could make him master of his world, the Morloo! Strange creatures from another dimension, this hyper-powered being bowed to do his will, although time and time again Merlin developed the means to counteract the Morloo's abilities, even employing one of his own! After five forays versus his opposite number, the Doctor called it quits on his career in villany.
Doctor Clever was the arch-enemy of Johnny Quick, second fastest man on Earth-Two. Employing various schemes like his counterpart to manipulate minds, he also tapped into extra-dimensional force although instead of a gigantic creature to do his bidding, it was the speed force which imbued his own henchman with superhuman abilities to face off versus Quick. Like Seven, Clever's various forays into felony failed.