It all depends how traditional you want to be. Originally, there were very few. There used to be a few common masculine first names which were the same as surnames, such as George, Gordon and James. Other common surnames were derivatives of first names, such as Johnson and Peters (meaning belong to the family of John or Peter). If you look in a phone book even today, you will see millions of people with the surname Johnson, but only a handful with the surname John. Over the centuries, it became common to give certain surnames, such as Harrison, to boys. Other names, such as Barclay, for example, were more common as surnames, but could be given to boys. Girls tended to have traditional feminine first names. These days, there is a 'free for all' when it comes to names. The distinction between what a first name and a surname should sound like has been all but lost. Nowadays, you can call your son - or your daughter - pretty well anything you like.

In the United States, it has long been common for families proud of their family to use surnames from the family history as first names for individuals. None of these names is particularly common. However, it is quite common to comment "that's an unusual first name" and be told "yes, it's an old family name." Some examples in which I think, but am not certain, that the first name is really a surname being used as a first name: Coleman Hawkins, the jazz musician Mason Williams, the composer and musician Gaylord Nelson, founder of Earth Day Harrison Ford, the movie actor