Gerhard Frankel
Gerhard Frankel was a 16th century scholar in the court of Holy Roman Emperor Rudolf II.
When the Mavora Collective invaded Prague and spread fear and hatred, Rudolf II gathered the greatest scholars in his court, including Frankel, to study a metal sphere that fell from the sky. After discovering that the sphere could turn thoughts into reality, Rabbi Judah Loew ben Bezalel used parts of the sphere to create the book The Sorrows of Prague, intended as a prison for the Mavora. Using the rest of the sphere, Loew created the Golem of Prague, a creature dedicated to truth. Since the sphere needed to be controlled by a living mind, Frankel volunteered, transferring his mind into the sphere and becoming the Golem.
As the Golem, Frankel imprisoned most of the Mavora into the book, though he had to seal the Mavora Queen, the greatest threat among them, underneath Prague. He continued to guard the seal of the Mavora Queen in a crypt beneath Wenceslas Square. However, the Golem was eventually found by Soviet art dealer Yuri Azarov with the guidance of the Mavora. Azarov then bonded with the Golem. Having stood guard for centuries, Frankel's mind was aged and weakened, allowing Azarov to twist him into a mindless henchman.
Meanwhile, The Sorrows of Prague was protected by a synagogue in Prague for many generations. In the four hundreds years that followed, its true origin and significance were forgotten, and Rabbi Saul Hoffman, its protector in 1989, believed that Frankel was its author.
After Frankel was ordered to free the Mavora Queen by Azarov, the Eleventh Doctor was able to free him from Azarov's control using genetic material from a cigar that Azarov discarded. Frankel explained his origin to the Doctor and asked him a question, "What... is buried... in man?", a question he was previously asked in Athens. However, because of the damage Frankel caused, the Mavora Queen was able to break through its seal. Frankel tried to confront the Queen once again, but his weakened state, coupled with his guilt from breaking the seal, allowed the queen to instantly disintegrate the Golem's body. (COMIC: The Broken Man)