Willi Schlage (24 December 1888 – 5 May 1940 in Berlin) was a German chess master and trainer. Active as a player during the inter-war years of the Weimar Republic and later as a trainer during the rise of the Third Reich, Schlage is remembered for a game depicted in the science fiction film 2001: A Space Odyssey, which chess writers attributed to him. He is also known for an endgame position attributed to a game played with Carl Ahues, frequently presented as an example in endgame literature.