Eifion may refer to:
Places: Eifion (UK Parliament constituency) in Caernarfonshire, Wales Lôn Eifion, part of Lôn Las Cymru, the Welsh National Cycle Route
A Welsh given name: Eifion Jones (1925–2004), Welsh marine botanist Eifion Jones (cricketer) (born 1942), Welsh cricketer Eifion Lewis-Roberts (born 1981), Welsh international rugby union player Eifion Williams (born 1975), Welsh footballer Eliseus Williams (Eifion Wyn) (1867–1926), Welsh language poet