Doctor Psycho discovered he could use ectoplasm, the substance found in the spirit world, and materialize it on Earth in whatever form he willed. He eventually discovered he could use Steve Trevor as a medium. After capturing Trevor, he used a machine to draw ectoplasm from Trevor's mind in the form of Trevor's idealized, super-powered fantasy image of himself. Doctor Psycho inhabited the ectoplasmic form and battled Wonder Woman using the name Captain Wonder. As Captain Wonder, Psycho fell in love with the Silver Swan (Helen Alexandros), an ugly young woman, whom the vindictive god Mars had transformed into a super-powered beauty. Both Captain Wonder and Silver Swan were defeated by Wonder Woman and eventually reverted to their original forms. Captain Wonder returns for one more battle against Wonder Woman, and teams with Silver Swan, Cheetah and Angle Man against Etta Candy (whom they wrongly believe is Wonder Woman).
Created from the fantasies of Steve Trevor, Captain Wonder has powers similar to Wonder Woman's, based on his fantasy only more intense (i.e., stronger, faster, etc.). Captain Wonder possesses superhuman strength, speed and agility. He is capable of true flight as opposed to what was then Amazonian flight, gliding on air currents. He wears Amazonian-style bracelets but it is unknown whether they functioned as Wonder Woman's bracelets do. He was able to take mental control of both Wonder Woman's invisible plane and her golden Lasso of Truth.