William King was born on December 3, 1890[1] in San Mateo, California, the son of Frederic Randolph King and Edith King (born Boswell).[2] He was the grandson of minister and noted orator, Thomas Starr King.[2]
As a freshman at the University of California, King was a member of the varsity rugby team.[3] While at the university, King played primarily at lock.[4][5] On November 16, 1912, King played for the United States at flanker in its first capped match against Australia—a 12–8 loss.[6] On November 15, 1913, King returned to the United States team, playing at number eight against New Zealand—a 51–3 defeat.[7] By August 1914, King had withdrawn from the University of California and was consequently no longer a member of the rugby team.[8]
After attending the University of California and playing for the United States team, King became a rancher.[2] William King died on July 1, 1937, at the age of 46.[1]