E! OnlinePrince George Celebrates His 3rd Birthday: How the Little Royal Is Already Showing the Makings of a Future KingE! OnlineToday one of our all-time favorite tots turns 3. Prince George, the boy who will one day be king has had quite an adventure during his short time on this planet: He's already met the president of the United States (while stealing the show in a ...Prince George Is 3!