William Clay, Willie Clay, Bill Clay, or Billy Clay may refer to:
Politicians Bill Clay (William Lacy Clay, Sr., 1931–2025), politician from the state of Missouri Lacy Clay (William Lacy Clay, Jr., born 1956), politician from the state of Missouri Sir William Clay, 1st Baronet (1791–1869), English merchant and MP for Tower Hamlets
Sports William Clay (footballer) (born 1883), footballer Willie Clay (born 1970), former American football player Billy Clay (born 1944), American football cornerback William Clay (cyclist) (born 1973), American track cyclist Bill Clay (baseball) (1874–1917), American baseball player
Others William Clay (industrialist), early user of the Bessemer process in Liverpool William Keatinge Clay (1797–1867), English cleric and antiquary Bill Clay, an alias of Hans Gruber, the main antagonist of Die Hard
See also William Clay Ford (disambiguation) Will Claye (born 1991), American athlete Clay (disambiguation)