Harold DuQuesne was a Human man, a Federation ambassador in the 24th century.
In 2372, Ambassador DeQuesne, T'Pao and Harold Strockman represented the Federation in peace talks held on Deep Space 9 that attempted to find a peaceful solution to the conflict between the Maquis and Cardassia. The peace talks were held by the Valtusians, but fell apart when it was revealed that the Valtusian ambassadors had been replaced by Changelings. (DS9 novel: The Heart of the Warrior)