Fennell may refer to:
- Alan Fennell (1936-2001), British writer and editor
- Albert Fennell (1920–1988), British film and television producer
- Dave Fennell (born 1952), former Canadian Football League defensive lineman
- Desmond Fennell (Irish writer) (born 1929)
- Eamonn Fennell (born 1984), Gaelic football player
- Frederick Fennell (1914-2004), American music conductor
- Jan Fennell, dog trainer and writer
- Jane Fennell, Australian former TV presenter
- John Lister Illingworth Fennell, British historian of Russia
- Joseph Fennell (1835-1919), Anglican priest
- Kevin Fennell, drummer for the American indie rock band Guided by Voices
- L. Raymond Fennell (1893-1986), Canadian politician
- Marc Fennell (born 1985), Australian film critic, technology journalist, radio personality and author
- Nuala Fennell (1935-2009), Irish economist and politician
- Patricia Fennell, American writer and businessperson
- Robert Fennell (born 1956), American politician and restauranteur
- Susan Fennell (born 1953), mayor of Brampton, Ontario, Canada
- Thomas Fennell (disambiguation)
- Willie Fennell (1920-1992), Australian actor and comedian