Thomas Duff Shawnessy and his wife Ellen were the parents of John (Johnny) Wickliff Shawnessy, the protagonist of Ross Lockridge's novel Raintree County. T.D. Shawnessy was supposedly the son of a Scotswoman Ellen Shawnessy by the schoolboy Thomas Carlyle.

Philip José Farmer discusses the family in his book Doc Savage: His Apocalyptic Life. He considers whether it is likely that Carlyle was T.D. Shawnessy's father, and also noted that Sam Spade was descended from T.D. and Ellen's daughter Faith.

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