It is likely that Blish got the name for his black magician from the titular character in Harold Frederic's 1896 novel The Damnation of Theron Ware.
Frédéric Chopin | Harold Pinter | Harold Wilson | Harold Macmillan | Harold Bloom | Harold Godwinson | Frederic Rzewski | Harold Lloyd | Harold Stassen | Harold Prince | Frederic Remington | J. Harold Ellens | Harold Holt | Sir Harold Hillier Gardens | Harold Washington | Harold Hitz Burton | Harold Alexander, 1st Earl Alexander of Tunis | Frédéric Joliot-Curie | Harold Peto | Harold & Kumar Go to White Castle | Harold Arlen | Harold | George Frederic Watts | Frédéric Artru | Harold Budd | Harold Eugene Edgerton | Harold Bauer | Frederic William Maitland | Frederic Hymen Cowen | Jean-Frédéric Phélypeaux, Count of Maurepas |
The Damnation of Theron Ware (published in England as Illumination) is an 1896 novel by American author Harold Frederic.