Valk
Valk was the second of the War Machines to be created. (PROSE: The War Machines [+]Ian Stuart Black, adapted from The War Machines (Ian Stuart Black), Target novelisations (Target Books, 1989).) It was captured by the First Doctor in a magnetic field. He then reprogrammed it to destroy WOTAN, which it did. (TV: The War Machines [+]Ian Stuart Black, Doctor Who season 3 (BBC1, 1966).)