Karl Marx's chess
"Marx adored chess," writes Daniel Johnson, "and—much to his wife Jenny's exasperation—would disappear with his fellow émigrées for days at a time on chess binges. Despite devoting so much time to chess, he never rose above mediocrity." One story has Marx so agitated about a late-night chess loss to a friend that he stalked over to his opponent's house early the next morning to demand a rematch.
—Shenk, David. The Immortal Game: A History of Chess. New York: Random House, 2006. Page 169.
There is one of Marx's games at Chessgames.com—he plays the King's Gambit Accepted (C36) in a casual game and wins.