Starr Saxon was a master robot-maker whose ability rivaled that of Doctor Doom. Deciding to use his genius for personal gain, Saxon began offering his robotic services to underworld clients. While carrying out a murder, one of Saxon's robots met and was thwarted by Daredevil. Seeking to make the crimefighter pay for his intervention, Saxon embarked upon an elaborate scheme, which culminated in his assuming the guise of Daredevil's old enemy, Mister Fear. In battle with Daredevil atop his hovercraft, Saxon fell hundreds of feet to the ground.
Unseen by Daredevil or the authorities, Saxon's robots, acting on pre-programmed instructions, retrieved the dying body of their inventor and brought him to his workshop. There they transferred his encephalic patterns into a computer system. When Saxon resumed a semblance of consciousness, he learned that his human body had died and that he now possessed a robotic body.
Though dismayed by his condition, Saxon constructed for himself a more human-looking body and resumed his business of custom-building robots under the name of Machinesmith. His new specialty was the construction of robotic simulacra that looked and acted exactly like their human models. His Baron Strucker robot was lifelike to the point that S.H.I.E.L.D. had had it under surveillance for a number of years before they discovered that it was a robot. He also created a Magneto robot that the mutant Mesmero believed was real for several months. Most of his clients remain unrevealed.
Despite his successes, Machinesmith grew to hate his pseudo-life, but found that his programming would not allow him to terminate himself.
Machinesmith was confronted by Night Thrasher and his incarnation of the New Warriors under the guise of stopping him from developing a techno-organic virus. Machinesmith was able to absorb the technology of the New Warriors' armor and seriously injured Decibel. He was defeated when Kaz uploaded a virus into his base's computer mainframe which caused the nanites within his technological armor to polarize and breakdown into "grey goo".