Mystery in Space #73 introduced Evan Wright, who could answer any question from any book he has ever read, but he would come in contact with a book he had heretofore not seen. Tied to the ancient Krell Empire that once dominated this sector of space, this was but one of many artifacts left behind by this seemingly extinct space race. And as indicated in World's Finest Comics #249 and Superman Family #192 (in February and November 1978 respectively), the exact same tale took place on both Earths One and Two! Talk about a twice-told tale! But it's what took place afterward in those two issues (plus one other later on) that we're interested in today. For you see, on Earth-Two in the early 1940's, Wonder Woman faced off against her old foe Doctor Psycho and his unwitting henchwoman Joan White (whose counterpart June Moone faced off against a different famous female on Earth-One, Supergirl, but we digress). And during this encounter, Princess Diana met Sgt Rock and his Easy Company of her world, as well as some descendents of the once proud Krell Empire. They were seeking to replicate their triumphant reign of peace throughout the galaxy, although they sought out a supervillain who was truly Psycho. At the end of this encounter, when they witness the heroism of the Amazing Amazon, they returned to space to continue their search for regions where they could reign unimpeded once more.
On Earth-One, Kal-El had contemplated using a Computer Probability Simulator what would happen had Krypton-One perished before he was born. A world without a Superman, how unthinkable this would be. The program led him to an alternate reality wherein his grandfather, Jor-El I, discovered that his world's existence was threatened. Only he was accompanied by a fellow scientist, Lor-Van, who had access to ancient Krull (derrivative of the "Krell" race) technology left behind on their planet. When Krypton-One was finally destroyed, not by internal tremors but by a passing comet, its sole survivors on board this vessel were the two intellectual's children, Jor-El's twin sons Jor-El II and Nim-El, and Lor-Van's daughter Lora. Arriving on Earth-One, these kids would be adopted by the Kents and Clarks!
However, would the actual Krell appear on Earth-One as they had on Earth-Two? Yes, only this would transpire two years later, in November 1980, when a strange object returned to Superman's adopted world after having departed years before. The floating Superman Island, a structure which Kal-El used to store all the Kryptonite he could locate on his adopted planet, had been floating in space until it was discovered by the last of the Krell in that universe. In a much weaker state than their counterparts in Earth-Two's dimension, these Krell depended on the Kryptonite radiation in order to survive. Seeing the image of their savior fashioned after the Man of Steel, they steered the man-made planetoid towards Earth-One in order to meet their unintentional savior. Although a scheme hatched by the criminal organiation known as the H.I.V.E. deprived them of their precision meteor rocks, Kal-El saved them once more, sending the island to a habitable planet.
Note the differences in the appearance between the two versions of the Krell, with one pinkish skin color and another with a bluish-green hue instead. Their style of clothing in also distinct, one preferring a superheroic look while the other clad in white robes and white space suits. While both seem to possess remarkable technology, the Krell-One people are definitely more dependent on their surroundings then were their Krell-Two dopplegangers. Regardless, both were peace-loving peoples who touched the heart of a Wonder Woman and a Superman from two parallel planets.