The first villainous version appears in the final panel of The Avengers #69 (Oct. 1969), the first chapter of a three-issue storyline by writer Roy Thomas and penciller Sal Buscema. The story arc introduced the supervillain team the Squadron Sinister, whose four members were loosely based on heroes in DC Comics' Justice League of America, with Doctor Spectrum based on Green Lantern.
The Squadron Sinister are created by the cosmic entity the Grandmaster to battle the champions of the time-traveling Kang—the superhero team the Avengers. Doctor Spectrum battles the Avenger Iron Man, and is defeated when the hero deduces that the villain's Power Prism (a sentient entity called Krimonn) is vulnerable to ultra-violet light. The Avengers eventually defeat the Squadron and they in turn are abandoned by the Grandmaster. Doctor Spectrum reappears in the title Iron Man and after a series of battles is defeated when Iron Man crushes the Power Prism. A powerless Obatu is arrested and deported back to his native Uganda. During a subsequent battle with The Thing, Black Panther and Brother Voodoo, Obatu accidentally falls to his death.
Unknown to Iron Man, the Power Prism reforms and is found by a sanitation worker, who eventually brings it to evangelist Billy Roberts, who after learning of the Prism's abilities becomes the second Doctor Spectrum.
The Squadron reappear in the title Defenders, reunited by the alien Nebulon (although the team is unaware of the fact that this a new Doctor Spectrum). The villains receive greater power in exchange for the planet Earth, and create a giant laser cannon in the Arctic to melt the polar ice caps, thereby covering the entirety of the Earth's surface in water. The superhero team the Defenders prevent the scheme and defeat the Squadron (and Nebulon), with Doctor Strange defeating Doctor Spectrum. After this defeat Doctor Spectrum and his two remaining team mates are teleported off world by Nebulon, returning with an energy-draining weapon. The Squadron Sinister plan to threaten the Earth again but are defeated once again by the Defenders and the Avenger Yellowjacket.
The Power Prism is kept by Yellowjacket, who decides to modify the gem and present it to his wife Janet Van Dyne (also the Avenger known as the Wasp). Krimonn, the entity within the Power Prism, possesses Jan and transforms her into a villainous female Doctor Spectrum, who battles several Avengers but is then defeated by the Vision's use of the Prism's ultraviolet weakness (Krimonn assumed in his arrogance that Iron Man had kept that information to himself rather than sharing it with others, thus 'giving up an advantage'). The prism itself bonds to the Wasp in an attempt to save itself, but is eventually removed by Billy Roberts after he is located by the Avengers. Roberts becomes Doctor Spectrum once more, although on this occasion the Power Prism is in control and seeks to bond with the most powerful Avenger, the Thunder God Thor. The Power Prism succeeds in taking Thor as a host, infecting Mjolnir to use as a focal point to control him and defeat the other Avengers, but fails to take into account that to wield Mjolnir, Thor must be "worthy". No longer worthy to wield the hammer due to him being tainted by the gem, Thor drops Mjolnir and reverts to his mortal alter-ego Donald Blake during a fight with Iron Man, which results in the Power Prism losing control and becoming inert, apparently forever.