William Parker may refer to:

• William Parker (musician) (born 1952), American jazz double bassist
• William Parker (screenwriter) (1886–1941), American screenwriter
• William Parker (Private Practice), character in the series TV Private Practice
• William Atticus Parker, (born 2004), American filmmaker and actor

• William Parker (privy counsellor) (c. 1465–1510), privy counsellor and standard-bearer to King Richard III
• William Parker (privateer) (died 1617), English captain and privateer, and also mayor of Plymouth
• Sir William Parker, 1st Baronet, of Harburn (1743–1802), British admiral
• Sir William Parker, 1st Baronet, of Shenstone (1781–1866), British admiral
• William Harwar Parker (1826–1896), United States Navy officer
• William Parker (Medal of Honor) (1832–?), American Civil War sailor and Medal of Honor recipient
• William Albert Parker, American Civil War Union Navy commander of James River forces

• William Parker (died 1403), member of parliament (MP) for City of London
• William Parker (died 1421), MP for Hertfordshire
• William Parker (fl.1410), MP for Great Yarmouth
• William Parker, 4th Baron Monteagle (1575–1622), English politician
• William H. Parker (politician) (1847–1908), US representative from South Dakota
• William Parker (Boston) (1793–1873), businessman and politician in the United States
• William Parker (MP for West Suffolk) (1802–1892), British Member of Parliament for West Suffolk, 1859–1880
• William Parker (Oregon politician), member of the Oregon Territorial Legislature, 1850
• William T. Parker (1928–2014), member of the Virginia Senate and House of Delegates

• William Parker (priest, died c. 1631), rose to archdeacon in two dioceses
• William Parker (priest, died 1802) (c.1749–1802), Anglican controversialist
• William Parker (bishop) (1897–1982), bishop of Shrewsbury in the Church of England

• Willie Parker (defensive tackle) (born 1945), former American football defensive tackle
• Willie Parker (offensive lineman) (born 1948), former American football center
• Willie Parker (born 1980), American football running back
• William Parker (Oxford University cricketer) (1832–1873), English cricketer
• William Parker (New Zealand cricketer) (1862–1930), New Zealand cricketer
• William Parker (MCC cricketer) (1886–1915), English cricketer
• William Parker (bowls) (1892–1979), English bowls player
• Will Parker (1873–1955), rugby union player
• Sir William Parker, 3rd Baronet (1889–1971), British rower and Olympic medalist
• Smush Parker (born 1981), American basketball player
• Tony Parker (William Anthony Parker II, born 1982), French basketball player

• William Parker (early settler) (1618–1686), settler in the Connecticut colony
• William Parker (builder) (1800–1854), St. John's, Newfoundland builder
• William Parker (abolitionist) (1821–1891), anti-slavery activist and freedom fighter
• William Parker (glassmaker) (?–1817), American glassmaker and inventor
• William Kitchen Parker (1823–1890), British physician and comparative anatomist
• William Parker (master) (1870–1953), Australian barrister in New South Wales
• William Belmont Parker (1871–1934), United States editor
• William H. Parker (physicist) (1941–), American physicist
• William H. Parker (police officer) (1905–1966), Chief of the Los Angeles Police Department

• Bill Parker (disambiguation)
• Billy Parker (disambiguation)