From Chesspedia, the Chess Encyclopedia

Curt von Bardeleben (1861-1924) was a count and a German chess master who committed suicide by jumping out of a window in 1924. His life and death were the basis for that of the main character in the novel The Defense by Vladimir Nabokov.

He is perhaps best known for the game he lost to the former world champion Wilhelm Steinitz at the Hastings tournament of 1895.