Deutscher aka Lyman is the unseen main antagonist of "A Sound of Thunder" by Ray Bradbury. He is a fascist who runs for, and later wins, presidential office in the USA.
Deutscher is mentioned at the beginning of the story when Eckels, Billings and Kramer are discussing the recent election and how lucky it is that a candidate named Keith won, because if his opponent Deutscher, who is mentioned to be against everything good and even referred to as "anti-christ", had won, they would be living in a fascist dictatorship. After they get back from their prehistoric hunting trip with Travis and Lespersance, Eckels notices that American English is now spelt differently and to his horror he discovers Deutscher has now won the election. He then realises that he stepped on a butterfly in prehistoric times, changing history, and cannot go back and stop himself due to the laws of time travel. Travis then kills Eckels as punishment for making Deutscher president, and it can be assumed that Deutscher is still in power.
Deutscher is called Lyman in the comic adaptation of the story, which also features Eckels simply being told he can't go back.