Bugi ab Gwynlliw Filwr[1] (also Hywgi,[2] Bywgi[3] and Beugi[4]) was a Welsh Christian saint in the 6th century.
He was reportedly the son of Gwynllyw, a Welsh king, brother of saint Cadoc and the father of Beuno (died 640), abbot and saint.[2] His wife (known as Peren,[5] Beren,[1] or Perferen[1]) was the daughter of Lleuddun Luyddog,[2] identified as King Lot of Lothian.[5]