Vladimir Lenin
From Memory Alpha, the free Star Trek reference.
Vladimir Ilyich Lenin was one of the most influential Human political figures of the 20th century on Earth. He led the Russian Revolution, which transformed Russia from a monarchy into a communist state.
The city of Leningrad was named in his honor.
In an alternate timeline, Lenin was assassinated by an unknown assailant in 1916. No one took Lenin's place and Russia never turned to communism. Because of this, Adolf Hitler focused on the west during World War II, and was able to attack and invade the eastern United States. (ENT: "Storm Front, Part II")
