Will has definitely replaced Bill, not only as a nickname for William but as a stand-alone name as well, partly thanks to England's Prince William, also known as Wills.
Will has a nice old-fashioned, down-home charm, and with recent references such as Will Smith, Good Will Hunting, and Will and Grace, it has taken on an air of understated cool.
Most celebrities known as Will were christened William—Shakespeare, legendary humorist Rogers, cartoonist Eisner, and actor Arnett—but others were not. Will Smith was born Willard and Will Ferrell was originally John William.
A key character on Glee was Will Schuester.