In the short story The Mystery of the Blue Jar, Professor Marchaud is the name of the man renting Heather Cottage. He is an elderly French professor suffering from consumption, and lives with his daughter in the cottage.
Professor Marchaud doesn't appear in the story, he is only mentioned.
Portrayals[]
The character credited as Marchaud in the 1982 adaptation, is a young man and Felise Marchaud calls him Pierre. He is the accomplice of Dr Lavington and Felise and possibly the fiancé of Felise.