Alltwen (or Allt-wen; translates to "white wooded slope") is a village in the Swansea Valley (Welsh: Cwmtawe) in Wales. Alltwen forms part of the community of Cilybebyll and is administered separately from adjoining Pontardawe on the opposite bank of the River Tawe. Alltwen is served by Alltwen Primary School and the village has a rugby union club, Alltwen RFC (Welsh: Clwb Rygbi Alltwen).