Elen (also known as Saint Helen of Caernarfon) was a late 4th century founder of churches in Wales who is remembered as a saint. Traditionally she is said to have been a Romano-British princess and the wife of Macsen or Magnus Clemens Maximus, Emperor in Britain, Gaul and Spain, where he died seeking imperial recognition in 388.

Church tradition
Elen was mother of five, including a boy named Constantine, but she lived about sixty years later than Helena of Constantinople, the mother of Constantine the Great with whom she has, in times past, been confused. She is patron of Llanelan in West Gower and of the church at Penisa'r-waun near Caernarfon, where her feast day is 22 May. Together with her sons, Cystennin (Constantine) and Peblig (Publicius, named in the calendar of the Church in Wales), she is said to have introduced into Wales the Celtic form of monasticism from Gaul. Saint Gregory of Tours records that Maximus (and Elen) met Saint Martin of Tours while they were in Gaul.

Literary tradition
Elen's story is told in The Dream of Macsen Wledig, one of the tales associated with the Mabinogion. Welsh mythology remembers her as the daughter of a chieftain of north Wales named Eudaf or Eudwy, who probably lived somewhere near the Roman base of Segontium, now Caernarfon. She is remembered as a heroine who magically built highways across her country so that the soldiers could more easily defend it from attackers, thus earning her the name Elen Luddog (Elen of the Hosts). She is said to have ordered the making of Sarn Helen (Fford Elan), the great Roman road running from Caernarfon to South Wales via Dolgellau, Pennal and Bremia (Llanddewi Brefi). Though this road bears her name it is considerably older than Elen's accepted time period. Many other roads in Wales bear her name (e.g. Llwybr Elen) and she is thus acknowledged as the patron saint of British roadbuilders and the protectoress of travellers.