The interweb has revealed the likely identify of the villain in The Amazing Spider-Man 2 to be the electrifying Electro. Electro first zapped his way into Spidey's life in 1964's Amazing Spider-Man #9 and has been a mainstay in Spider-Man media ever since. As a founding member of the Sinister Six, Electro is one of the better members who has yet to make his live action debut.
Electro first did the electric boogaloo in a cameo appearance of The Marvel Super-Heroes during the Namor episode, Dr. Doom's Day.
In the 1981 series, Spider-Man and His Amazing Friends, Electro made another shocking return in the episode Videoman, which brought an arcade game to life.
Due to a planned appearance in an in development live action series, Electro was shelved for most of the 1990's Spider-Man animated series run, though he finally debuted during the series final season.
Most recently, Electro donned an electric containment suit to do battle with the Web-head on the animated Spectacular Spider-Man.