There are two versions of Simon Ryker in the Marvel Universe, one from Earth-616 (mainstream Marvel) and one from Earth-7484 (Earth-Deathlok).
The first one was a scientist serving the military of the United States. He created the Symbionic Man, a cyborg, but his creation lacked a lifeforce. Determined to find a power source for his creation, Ryker worked on a military ship. When the ship coincidently encountered Namor
and Dr. Doom
fighting each other, Ryker viewed an opportunity. He approached Doom from behind and used a device to drain energy from the Latverian's armor. The energy was sufficient to bring the Symbionic man to life. Doom spared Stryker's life and left him tending to his cyborg. Ryker later used the Symbionic Man in an attempt to drain Namor's life energy. The fight resulted in the death of the cyborg.
The Second Origin
The second Ryker's story starts at this point. His battles with Doom and Namor in this world resulted in Simon becoming crippled from the waist down. His brother Harlan Ryker (Hellinger) offered to helpe him and turned him into a cyborg. His legs, spine and parts of his brain were all cybernetic. His only superhuman power was the ability to connect his brain directly to computer systems. He would later use a powerful computer to take over all computer systems in New York City.
Simon appeared human to outsiders and was able to serve in the military alongside Luther Manning. When Manning was killed in a bomb explosion, Simon was the one authorising the conversion of his remains to another cyborg. Thus Deathlok
was created. The junior cyborg would soon rebel. His conflicts with Simon ended with the latter becoming insane.