Maxwell "Max" Dillon was an electrical engineer formerly employed at Oscorp Industries, mostly being seen as a "nobody" by his co-workers due to his low-ranking job at the corporation.
After having to stay behind at work on his birthday, Max had to fix a broken power line. He climbed all of the way up to the line and balanced on a railing. He was able to successfully plug the line back in, fixing the circuit. However, before he could get down, Max was shocked with electricity, making him fall down in to a tank of genetically-modified electric eels. He was attacked by the eels, before finally breaking the entire tank. Following this accident, Max mutated into a being of pure electrical energy, was given a containment suit by his rescuer Doctor Otto Octavius, and dubbed himself Electro thanks to an inspirational quip from Spider Man during their first confrontation.