The Puppet Master uses radioactive clay to make puppets of people that he can then control, attaching them to strings and moving them as puppets, presumably he has some sort of psionic ability that enables him to do this. He is the step-father of Alicia Masters, a blind girl who holds an attraction to Thing. He once tried to take over the world but was thwarted in this effort by the Fantastic Four.
The man who would become the Puppet-Master was born in a small Balkan nation. He moved to the United States as a young man. He was socially maladjusted and had no friends. After he finished college he went into business with Jacob Reiss. Philip was jealous of Reiss' wealth and of his family and decided to sabotage his workplace, but Reiss caught him in the act and when the two fought Reiss was accidentally killed in an explosion. Unfortunately, Reiss' daughter Alicia was caught in the explosion and blinded as a result.
Playing the explosion off as an accident, he started a relationship with and then married Reiss's wife, Marcia, and adopted Alicia. When his wife died it was more than he could bear and he lost his sanity. It was at this time that he first began experimenting with radioactive clay that he was somehow able to use to psionically control specific individual's bodies. He thought to exploit this talent to the fullest and drew up a plan to take over the world. He didn't get very far with the plan before the Fantastic Four stopped him.
He was once thought to have been killed when he fell out of the window of a fairly tall building, but he miraculously survived. Later on, he was transformed into living clay. Yet, he was eventually returned to normal.
He has frequently been an ally of Doctor Doom.