Leon Trotsky was a central Bolshevik communist leader of Russia in 1918, after the Russian Revolution of 1917. (AUDIO: Last of the Romanovs) He eventually fell out of favour with Joseph Stalin and the Stalinists, who were an unforgiving group. (PROSE: Spiral Scratch) Trotsky died from an ice pick to the head (AUDIO: Last of the Romanovs) in August of 1940. (PROSE: Sometime Never...)
References
In order to escape capture from Bolshevik guards, Ian Chesterton said he was sent to Ekaterinburg from Moscow by Vladimir Lenin, Stalin and Trotsky and that he knew what would happen to them in the future as a distraction. He told them how Trotsky would die, but then claimed to Makerenkov, his fellow escapee, that he made it up. (AUDIO: Last of the Romanovs)
Upon encountering the Ninth Doctor in 1924, Colonel Oblonsky suspected he was a Bolshevik agent sent by Lenin or Trotsky. (PROSE: The Clockwise Man)
The Ministry of Defence had reservations about hiring Julian St Stephen because they suspected he could be a Trotskyite and supporter of socialism. (AUDIO: Artificial Intelligence)