Kurt Schalk

Hauptsturmführer Kurt Schalk was a Nazi scientist and the creator of the persuasion machine. He recognised Elizabeth Klein thinking her to be someone else. He told Will Arrowsmith about the creatures that were looking for the amachine, including the Sontarans. (AUDIO: Persuasion) To prevent the machine from falling into the wrong hands, he used the machine on himself and his assistant Lukas Hinterberger to make them believe they were each other. Thus, anyone who would come seeking the machine would focus on Hinterberger instead of Schalk. (AUDIO: Starlight Robbery)

He was also the biological father of Elizabeth Klein. (AUDIO: Daleks Among Us)

Behind the scenes
Because of the identity switch, in Persuasion the credit for playing Schalk went to David Sibley.