Known by many names, Max Eisenhart, also most commonly known as Erik Magnus Lehnsherr, was born and raised in Nuremberg, Germany by a middle class Jewish family. During his youth, Max endured atrocities performed by the Nazi dictatorship in Auschwitz. After escaping, he learned that he was a mutant with the ability to generate and control magnetic fields, a condition that caused additional hate and fear from those who were different from him.

Eventually he traveled to Haifa, Israel, possibly under the guise "Erik Magnus". Magnus worked there as a volunteer orderly at a psychiatric hospital for Holocaust victims. It was there Erik first met and became friends with Charles Xavier. Magnus and Xavier frequently debated the subject of mutants' coexistence with the rest of humanity. While Xavier was idealistic, and believed that humans and mutants could co-exist, Magneto's experiences had hardened him, and he had come to believe that humanity would never allow mutants to live in peace.

After being a target for so long, the "Master of Magnetism" explicitly rejected the possibility of any harmony with humans, aiming to conquer the world to enable mutants, whom he refers to as Homo superior, to become the dominant species. Adopting the mutant name Magneto, he decided to disseminate his beliefs by employing brute force with terrorist attacks.

Magneto has fathered many children over the years, though most have died. His known children are Quicksilver, Scarlet Witch and Polaris.