Lady Marie Ernhardt
was the wife of Lord Ernhardt
during the 19th century
. After suffering radiation poisoning
from a crashed Cyber-ship
, she died. However, unbeknownst to her husband, her body was recreated by the Watchman
scavenged from the same ship. In consequence, she gained inhuman strength and immortality.
When the Cybermen started an attack on the village, she assisted the Eleventh Doctor and Olga Bordmann in stopping them from recharging their energy. She survived the attack on her castle but lost her son in the process, who had been augmented with a cyber body just like herself. (PROSE: Plague of the Cybermen)