The puppet of Mary Shelley was one of the wooden puppets created by Gramm using Cyber-Technology after Mary Shelley was put into his cage.
Being modelled on Mary in appearance, the puppet could also talk with Mary's voice, learning and repeating phrases spoken by Mary. Unlike Mary, who had hazel eyes, her puppet's eyes were blue. Johan Drossel intended but failed to "complete" the puppet by supplying it with the eyes of the original.
The Eighth Doctor briefly mistook the puppet for the real Mary, when the puppet was sent to bring him to Gramm. Trying to escape, the Doctor found Mary talking to his own puppet. The Doctor and Mary managed to distract each puppet by the other puppet and get away. The puppets of the Doctor and Mary then destroyed each other.