Doctor Octopus's History
Doctor Otto Octavius had relatively benign beginnings. Before his transformation into the megalomaniacal archenemy of the web-slinger, Otto was a brilliant and respected nuclear physicist, inventor, and lecturer. He designed a set of highly advanced mechanical arms to assist him with his research into atomic physics. The tentacled arms were resistant to radiation, capable of great strength and highly precise movement and were attached to a harness that fit around his body.
In an accident, the apparatus became fused to his body, and he gained the ability to control the movement of the arms using his thoughts alone. The accident also seemingly damaged his brain (though it was later suggested that what was interpreted as brain damage was in fact his mind rewiring itself to accommodate four extra limbs), and the once timid scientist turned to a life of crime. Later, the harness was surgically removed, but he was still able to control it mentally, even at a distance. While wearing the harness, the arms are powerful enough to allow him to walk up sheer concrete walls and move quickly about.
During the Clone Saga, Doctor Octopus was murdered by the insane Peter Parker clone named Kaine. Octavus's student Carolyn Trainer took over as "Doctor Octopus" until the original was resurrected by a branch of the mystical ninja cult known as the Hand. Although Octavius had discovered Peter Parker's dual identity shortly prior to his death, he lost all knowledge of it upon his resurrection.