The name Fitz is a boy's name of Scottish origin meaning "son of". Fitz and is often added to lists like Cool Baby Names That Start With F and discussed in our forums with posts like "Favorite Full name for Nickname".
From the experts:
Any number of Fitz names -- Fitzgerald, Fitzpatrick, Fitzroy, Fitzwilliam -- have been used as Christian names, in fact Fitzwilliam was the given name of the dashing Mr. Darcy in Pride and Prejudice. Fitz can be a short form of any of them and is often, like Mac, a nickname drawn from a surname.