The term 'Master of the Macabre' is often used to refer to the American writer Edgar Allan Poe. Poe was a poet, short story writer, and literary critic who is best known for his dark and mysterious works such as 'The Raven' and 'The Tell-Tale Heart'. His writing style has been described as gothic, horror, and macabre, and he is widely considered to be one of the most influential writers in American literature. The three letter solution to the crossword is POE, which is the surname of Edgar Allan Poe.