William \wi(l)-liam\ as a boy's name is pronounced WIL-yum. It is of Old German origin, and the meaning of William is "will helmet, protection". For a long time after the Norman conquest in AD 1066, three out of four English boys were given some form of the conqueror's name, William. Short forms and variants came into being with a common basic meaning of "will", "determined", or "resolute". William has remained a royal name in the UK for nearly one thousand years. The firstborn son of the current Prince of Wales is named William. Wilhelm is a German form; actor Willem Dafoe has made the Dutch form familiar since the 1980s. See also Willard. Playwright William Shakespeare; actors William Hurt, Billy Crudup, Bill Pullman; film director Wim Wenders; poet William Blake; author William Faulkner; American Presidents William H. Harrison, William H. Taft, William McKinley; Bill Clinton.
William has 34 variant forms: Bill, Bille, Billie, Billy, Guglielmo, Guillaume, Guillermo, Liam, Vilhelm, Villem, Wilek, Wiley, Wilhelm, Wilhelmus, Wilkes, Wilkie, Wilkinson, Will, Willem, Willhelmus, Willi, Williams, Williamson, Willie, Willis, Willkie, Wills, Willson, Willy, Wilmer, Wilmot, Wilmott, Wilson and Wim.
For more information, see also the related name Bo.