Calon Lân is a Welsh hymn, the words of which were written in the 1890s by Daniel James (Gwyrosydd) and sung to a tune by John Hughes. The song is a hymn, and it has become associated with Welsh rugby union, being sung before almost every Test match involving the Welsh national team.
In 2007 the song was one of the traditional Welsh songs to make it to the screen in an S4C television series Codi Canu, an attempt to bring traditional four-part harmony choral singing back to the Welsh rugby terraces.
Calon Lân is unusual among the most popular Welsh traditional songs in that an English language version of the words is virtually never sung (unlike, for example, Cwm Rhondda), but the tune does appear, for example, in the British Methodist hymn book, Hymns and Psalms, set to the lyrics of "I will Sing the Wondrous Story" by P. P. Bliss. Bryn Terfel recorded "Dafydd Y Garreg Wen" on his 2000 album We'll Keep a Welcome.