Finding notable people in one's family tree is part of the fun of genealogy. There are several good resources for researching your celebrity ancestors.
Who hasn't studied their family tree with the hopes of finding some distant celebrity relative, or even some family royalty?
Well, I suppose that if you trace your family line back far enough, you will eventually find some notable ancestors. Not to brag, but my own family is connected to the British royal family. If I remember correctly, the Queen of England is my 21st cousin, once removed. My grandmother's family is directly descended from Princess Elizabeth of England (daughter of King Edward I).
There are several websites that specialize in family tree records for celebrities and royalty. You just might be shocked to find out who you're related to.
A collection of celebrity family trees, including a number of popular TV and movie stars. Some trees go back for 5 or 6 generations, but some are sparse with only a few ancestors listed.
Genealogy of the presidents of the USA
Family trees for all the men who have been president of the United States. Most only go back for 2 or 3 generations.
Directory of Royal Genealogical Data
I've used this site extensively in my own family tree research. More than 30,000 individuals from royal families across the globe. A must-visit site for anyone with royal connections in their tree.
Part of Cyndi's excellent genealogy site, with a huge list of sites dedicated to celebrity genealogy. I found that many of the links to genealogy.com are broken though. Still plenty to browse through.
Another database of royalty that focuses on the royal houses of England and Scotland. Of course with all the inter-marrying that takes place between royal families, there area also many entries for people outside of the British Isles.
Researching Your Famous and Infamous Ancestors
Not a database, but another helpful article for anyone doing research on famous relatives.