The Birth: Otto Octavius was one of the most brillient atomic researchers in the States till that tragic day which transformed him into one of the most deadliest villians of all. Dr. Otto Octavius was nicknamed Dr. Octopus while he was working at the U.S Atomic Research Center; the reason being, he had invented himself extendable metal "arms" attached to a harness which enabled him to work with toxic materials behind the lead walls that shield him from radiation.
Unfortunatley for him, one of his experiments went haywire, leading to an explosion. Though Dr. Octopus survived the blast, his metal arms were adhered to his body permanently and he had suffered permanent mental impairment. His brain acted in a bitter way to the doctors suggestions - he thought they were keeping him prisoner in the hospital to prevent his research since they were jealous of him. So he decided to escape from his "prison" and that's when he discovered that his artificial arms could now be controlled by his mere thought. Kepping the nickname given to him by his colleagues at the lab, he ventured out into the world of crime.
Doc Ock (As Spidey affectionately calls him) first appeared in Amazing Spider-Man #3.

The Legend: After duking it out with Spider-Man and defeating him Dr. Octopus escaped from the hospital and took over the U.S Atomic Research Center as his base to continue his research. His defeat against Doc Ock left Peter Parker thinking like a quitter, a mistake that was soon corrected by the words of The Human Torch, who had come to Midtown High to make a small speech to the class.
With renewed courage Spidey took on Doc Ock and as in a clichéd comic book ending, defeated Dr. Octopus.
Dr. Octopus can use his artificial arms for just about anything, from scaling high wall and leaping over traffic to punching out anyone who gets in his way; and that includes Spider-Man. It has also been mentioned that if the arms were to be surgically removed they might injure the good doctor fatally.
Doc. Ock seems to be a persistent topic in the Parker household. First, he had unmasked Spidey and till today thinks his mind played tricks on him when he saw the fragile Peter Parker under the mask. Also, he had won over the heart of May Parker who believed that Doctor Octavius was being persecuted for his genius by the authorities. She almost wound up marrying the Doctor. The Doctor also had a devoted girlfriend; Stunner, who unfortunately died later.
Dr.Octopus was also responsible for the death of Captain Stacy, Gwen Stacy's father. It was not a deliberate attempt, Spider-Man and the Doc were belting it out on the rooftops when a part of the building broke off and fell to the ground, hitting Captain Stacy fatally.
Doc Ock had also teamed up with the Black Cat for a short while, as the partnership went sour he held the grudge with a determination to destroy her.
Octopus was also well thought of as an organizer by the criminal community at large, resulting in the repeated formation of the Sinister Six, a group of Spidey villains determined to bring down the Webslinger, and its spin-off team, the Sinister Seven.

With Doctor Octopus' death, and the urge of Marvel to bring back old characters, a new Octopus appeared on the scene -a female.
........ She was Carolyn Trainer, daughter of spider-clone Ben Reilly's friend, Dr. Seward Trainer. She had been imfatuated with Doctor Octopus even before he became a villain. When the Doctor was imprisoned, Carolyn visited him in prison to cheer him up.
Carolyn soon became an expert on virtual reality programming. With Doctor Octopus' help she created Stunner and the Master Programmer. But soon afterwards, Doctor Octopus was killed. Enraged Carolyn Trainer took the guise of her mentor and became the "new and improved" Doctor Octopus.
Her origin was deatailed in Spider-Man Unlimited #18. But Carolyn made her debut as Doctor Octopus in Amazing Spider-Man #406.
Before her actual origin, she also had a small cameo in Amazing Spider-Man #405 where she kidnapped her father Dr. Seward Trainer to learn his secrets. When Scarlet Spider rescues Seward, Carolyn does not confront the arachnid directly.
She became known only when she invaded Seward Trainer's lab and fought the Scarlet Spider and Spider-Man. Proving more competent in combat than her predessesor, she escapes with Seward as her prisoner.
The two spiders crash into her underwater lab and recue Trainer from her clutches.
Later on, Carolyn also faces competition from from a gang led by Mr.Tso who also want control of the Virtual Reality information. With her knowlegde Carolyn creates a virtual reality bomb which was successful in transporting the public on Fifth Avenue to the Jurassic Era. Mr. Tso is thwarted by Carolyn when she blows up an entire building with her own men inside rather than let her competition lay hands on the VR devices. But the main peice of equipment; a VR visor falls in the unsuspecting hands of the Scarlet Spider. With Seward Trainer's help the spider and Trainer enter the VR world where they are detected by the Master Programmer (a digitized version of the original Doctor Octopus' mind). The Master Programmer sends his centurion; VR-37 to attack the duo in cyberspace. In the battle that follows, the Scarlet Spider escapes but Seward Trainer is "killed" in cyberspace, transforming him into a mindless vegetable.
Carolyn was unaware that Seward's mind was locked in cyberspace, a fact that was used against her advantage. Seward spied on Carolyn and reported back to Scarlet Spider.
She also hired the hitman; Pro to eliminate Mr. Tso. The assasination was foiled by Ben Reilly who then becomes Mr. Tso's bodyguard.
Not one to give up, Carolyn sends Aura, Override and the Looter after Tso's VR devices. Again they are thwarted by Scarlet Spider and get arrested. That's when she gets really steamed up. She revives the old experiment to create Stunner. A woman named Angelina Brancale becomes the driving force behind the Virtual Reality Stunner. The new Doc Ock also uses F.B.I. agent Joe Wade's life force to create a virtual reality Scarlet Spider to wreak havoc in NYC. This forces Ben Reilly to give up his Scarlet Spider disguise and adopt the guise of Spider-Man. (Spidey had recently given up his mask for a greater responsibility) Carolyn also completes her work on the "Virtual Reality Wave Generator" which merges reality and virtual reality and allow the Master Programmer to survive in the real world. But as soon as the Master Programmer is brought out into the open, the new Spidey spoils Doc Ock's fun.
Doc Ock then tries to steal her father's body from the hospital but as usual is thwarted by Spider-Man (Ben Reilly) and she finally gets arrested.
Much afterwards, Doctor Octopus escapes prison only to learn that her beloved Otto Octavius' body has been stolen for a revival experiment. She tracks down the body to Rose, Delilah, and the Hand as they are preparing to try to resurrect Octavius. Another uninvited guest that turns up is Spider-Man.
The crooks planned to use Spidey as a life force for Otto Octavius but he soon squirms out of the position. So the experiment proceeds with Stunner as the new volunteer. The original Doctor Octopus is finally resurrected from the dead but has a memory impairment. He no longer remembers that Peter Parker was the Spider-Man. Guess Marvel thought the new Doc Ock was not that great so they brought back the real deal.
With Otto alive, Carolyn turns her octopus arms over to him and has not been seen since.

Amazing Spider-Man #3	Amazing Spider-Man #406