Helen McCloy, born as Helen Worrell Clarkson McCloy (she also published as Helen Clarkson), was an American mystery writer, whose series character Dr. Basil Willing debuted in Dance of Death (1938). Willing believes that "every criminal leaves psychic fingerprints, and he can't wear gloves to hide them." He appeared in 13 of McCloy's novels and in several of her short stories. McCloy often used the theme of doppelganger, but in the end of the story she showed a psychological or realistic explanation for the seemingly supernatural events.