Leon Trotsky (1879-1940), born Lev Davidovich Bronshtein, was a revolutionary socialist and, with Lenin, leader of the Russian Revolution. From 1917-1924 Trotsky was commissar of foreign affairs and of war in the Soviet Union. He is often regarded as the founder of the Red Army.
Trotsky was forced to leave the country in 1928 during Stalin's rise to power. He spent much of the rest of his life in an attempt to set up an international communist party. During his exile, Trotsky continued to contribute to both the theory and practice of revolutionary Marxism, further developing his theory of the permanent revolution, tirelessly criticizing the degradation of socialism in the USSR, and founding the Fourth International as an alternative to the Stalinist Comintern. He died in Mexico as the result of a fight with an assassin sent by Stalin. Although the assassin was aprehended, Trotsky was himself fatally wounded with an ice pick and died several days later. The assasin was imprisoned by the Mexicans, and later returned to a hero's welcome in the Soviet Union.
Much of Trotsky's writings are available on-line at http://www.marxists.org.