William Klein

Bill, Will, Willy, Willie or William Klein may refer to:

• William Klein (photographer) (1926–2022), American-French photojournalist and filmmaker
• Will Klein (baseball) (born 1999), American professional baseball player
• Willie Klein (1901–1957), American champion golfer
• Willy Klein (1912–2004), Luxembourgian Olympic gymnast in 1936
• Bill Klein (businessman) (born 1948), American high-stakes poker champion
• Bill Klein, American football end in 1950 NFL draft
• Bill Klein, American businessman on 2009 TV reality series The Little Couple