Keltor Jacobs was the creator of the Galateans. When they were activated prematurely and started to kill people, he tried to use an electromagnetic pulse to deactivate them. Before he could do this, Chiyoko killed him.
When the Doctor and Amy traveled back in time and rewrote these events, Alan Turing's Galatean duplicate convinced the Galateans to stand down, and Keltor began to live with his creations. (COMIC: The Child of Time)