The fictional sleuth crossword solution for the term 'Fictional Sleuth Cross' is ALEX, which is a four letter word. ALEX is a popular fictional sleuth character created by author Agatha Christie. He is a Belgian detective who solves mysteries with his sidekick, Dr. Watson. ALEX is known for his intelligence and wit, as well as his ability to solve complex cases. He has appeared in many books, films, and television series over the years.