Cei is a surname, and may refer to:
- Giuseppe Cei (1889–1911), Italian aviation pioneer
- Giuseppe Cei (bishop) (1640–1704), Roman Catholic prelate
- Idilio Cei (1937–1996), Italian football goalkeeper
- Luca Cei (born 1975), Italian racing cyclist
- Pina Cei (1904–2000), Italian stage, film and television actress
- Sir Kay, in Arthurian legend