William Dyer may refer to:

• William Dyer (settler) (1609 – c. 1677), early settler of the Colony of Rhode Island and Providence Plantations
• William Dyer (cricketer) (1805–1865), English cricketer of the 1830s
• William John Dyer (1830–1909), New Zealand businessman and politician
• fictional character William Dyer, the narrator of H. P. Lovecraft's novella At the Mountains of Madness
• William J. Dyer (1881–1933), American actor
• William A. Dyer (1903–1993), American journalist
• Bill Dyer (Australian footballer) (1917–1957), Australian rules footballer
• William G. Dyer (1925–1997), American educator
• Willie Dyer (born 1987), Scottish footballer
• William Dyer (died 1681), 1st Dyer Baronet of Tottenham from 1678–1681
• Bill Dyer (20th century), American broadcaster at two Major League Baseball All-Star Games

• Dyer (surname)