The first Crypto-Man was constructed by Jasper Whyte, who wanted to create an army of them. He sent his construct out on an rampage to draw Thor's attention. Once he did get the Thunder God;s notice, the construct siphoned half of Thor's energy. Thor eventually talked Jasper into committing an selfless act by destroying his construct.
Crypto-Man was created by Stan Lee and Jack Kirby in 1970 and first appeared in Thor # 174.
The second Crypto-man, associated with the death of Jarella, was created by an uncredited scientist. The scientist had recreated him from the scraps of the original, but also doubled his power. Crypto-man absorbs power that he is hit with. The Hulk defeated him after a barrage of punches that overpowered his generator and fed back into the scientist's lab causing an explosion that would leave the scientist's corpse unidentifiable.