William, Bill, Billy or Willie Slater may refer to:

• William Slater (cricketer) (1790–1852), English cricketer
• William Slater (swimmer) (born 1940), Canadian swimmer
• William Slater (architect) (1819–1872), English architect
• William A. Slater (1857–1919), American businessman, art collector, and philanthropist
• Bill Slater (footballer) (1927–2018), English footballer
• Bill Slater (broadcaster) (1902–1965), American educator, sports announcer, and radio/television personality
• Bill Slater (politician) (1890–1960), Australian lawyer, politician and diplomat
• Billy Slater (born 1983), Australian rugby league footballer
• Billy Slater (footballer) (1858–?), English footballer
• Willie J. Slater, American football coach and player
• Edward Slater (1917–2016), also known as Bill Slater, Australian biochemist

• Derek Stevens
• Derek St. Holmes
• Derek Stiles
• Derek Stillie
• Derek Stirling
• Derek Stokes
• Derek Strong
• Derek Swan
• Derek Talbot
• Derek Tangye
• Derek Tatsuno
• Derek Taylor (cricketer)
• Derek Taylor (EastEnders)
• Derek Temple
• Derek the midget
• Derek the Midget
• Derek the sheep
• Derek the Sheep
• Derek Thomas (basketball)
• Derek Thompson (baseball)
• Derek Thompson (musician)
• Derek Tice
• Derek Tidball
• Derek tidball
• Derek Tracey