Doctor Eclipse is a Valiant Comics character, a foe of Solar, Man of the Atom. He was originally Fred Bender, but after being defeated by Solar and left to die in the desert, he sought Master Darque and asked him to replenish his powers.
Master Darque was himself a foe of Solar, so he agreed and transformed Fred Bender into Doctor Eclipse (Secret Weapons #1, September 1993). He proved to be a major threat for Solar and other heroes.
References
Doctor Eclipse Wikipedia(Text) CC BY-SA