William of Ockham
The fictional friar, William of Baskerville, alludes both to the fictional sleuth Sherlock Holmes and to William of Ockham. The name itself is derived from William of Ockham and Sir Arthur Conan Doyle's book "The Hound of the Baskervilles". Another view is that Eco has created Brother William as a combination of Roger Bacon, William of Ockham and Sherlock Holmes. (William himself notes that Bacon was a mentor of his and cites his ideas several times in the course of the book.)