As an English name, it became popular due to the Fleetwood Mac song Rhiannon (1976), especially in the United Kingdom and Australia.
Geoffrey based parts of Merlin's character on Myrddin Wyllt, a legendary madman and prophet who lived in the Caledonian Forest. Other parts of his life were based on that of the historical 5th-century Romano-British military leader Ambrosius Aurelianus (also known as Emrys Wledig). In Geoffrey's version of the tales and later embellishments Merlin is a magician and counselor for King Arthur.
This name became very popular in the second half of the 20th century. It reached the top ten names for boys in France (by 1997), Belgium (1998), Denmark (2003), Canada (2008), the Netherlands (2009), New Zealand (2009), Australia (2010), Scotland (2013), Spain (2015) and the United States (2018).
Gawain was a popular hero in medieval tales such as those by Chrétien de Troyes, where his name appears in the French form Gauvain or Gauvains. He is the main character of the 14th-century anonymous poem Sir Gawain and the Green Knight, in which he accepts a potentially fatal challenge from the mysterious Green Knight.
Notable bearers of this name include the early 6th-century saint Falco of Maastricht (located in the south of what is now the Netherlands) and the Austrian singer and musician Falco (1957-1998).
This name appears briefly in a poem in the Black Book of Carmarthen in the form Kyrridven [1] and in a poem in the Book of Taliesin in the form Kerrituen [2]. Some theories connect her to an otherwise unattested Celtic goddess of inspiration, and suppose her name is related to Welsh cerdd "poetry".