Keil is a surname, and may refer to:
- Alfredo Keil (1850–1907), Portuguese romantic composer and painter
- Alphonso Keil (1944–2008) Samoan born rock & roll musician, founding member of The Zodiacs and The Kavaliers
- Eliza Keil, Samoan born singer and member of Keil Isles
- Herma Keil, Samoan born rock & roll singer of the 1960s and lead singer of the Keil Isles
- Francisco Keil do Amaral (1910–1975), Portuguese architect, composer, painter, and photographer
- Franz von Keil (1862–1945), Austrian naval officer
- Freddie Keil (19?? - 1994), Samoan born rock & roll singer and lead singer of the Keil Isles
- Johann Friedrich Karl Keil (1807–1888), German Bible commentator
- Josef Keil (1878–1963), Austrian historian, epigrapher, and archaeologist
- Klaus Keil, American astronomer and father of Mark Keil
- Lillian Kinkella Keil (1916–2005), American flight nurse
- Mark Keil (b. 1967), American tennis player and son of Klaus Keil
- Olaf Keil(b.1934), Samoan born guitarist and founder of the Keil Isles and custom guitar builder for Fender
- Peter Keil (b. 1942), German painter
- Susanne Keil (b. 1978), German hammer thrower
- William Keil (1812–1877), American founder of communal religious societies