War Machine
War Machines were robots designed by WOTAN and built by its human slaves in its plot to conquer Earth. Only two War Machines were ever activated.
The first War Machine attacked a group of soilders despite heavy fire and remained undamaged. Before it could kill the remaining soilders and the Doctor it shut down as it was incomplete.
The second War Machine was captured by the Doctor and reprogrammed to destroy WOTAN which it did successfully. (DW: The War Machines)
Centuries in the future, historians of New Jupiter mistakenly believed that the War Machines were designed by the General Post Office to deliver mail. Consequently, replicas of War Machines were part of the Twentieth Century section of the EarthWorld tourist park. (EDA: EarthWorld)