David Llewellyn may refer to:

• David Llewellyn (Australian politician) (born 1942), member of the Parliament of Tasmania
• David Llewellyn (British politician) (1916–1992), British Member of Parliament for Cardiff North, 1950–1959
• David Llewellyn (author) (born 1978), Welsh novelist
• David Llewellyn (golfer) (born 1951), Welsh golfer
• David Llewellyn (rugby union) (born 1970), Wales international rugby union player also known as Dai
• David Llewellyn (academic) (born 1960), Vice-Chancellor of Harper Adams University
• Sir David Llewellyn, 1st Baronet (1879–1940), Welsh industrialist and financier
• David Llewellyn (trade unionist) (1907–?), Welsh trade unionist and political activist
• Dai Llewellyn (Sir David Llewellyn, 4th Baronet, 1946–2009), socialite
• David Herbert Llewellyn (died 1864), doctor who went down with the CSS Alabama
• David Llewellyn (footballer), (born 1949), footballer with West Ham United and Peterborough United

• Dafydd ap Llewelyn (disambiguation)
• David Llewellin (born 1960), Welsh rally driver