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 was originally written as a hymn, but has become firmly established as a rugby anthem, associated with the Welsh rugby union, being sung before almost every Test match involving the Welsh national team – though more likely to be heard sung at matches involving the Welsh football team in recent years. 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.

In 2012, the Welsh group Only Boys Aloud sang "Calon Lân" on the British ITV show Britain's Got Talent, coming third in the final. It has since become the most watched Welsh-language video on YouTube.

"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 Francis Harold Rowley. Hymn 223, The English singing translation by Rees Harris (1874–1954) appeared in The Abingdon Song Book in 1937.

A Spanish-language version of the song exists, sung mostly by Welsh Argentines in Y Wladfa, the former Welsh colony in Patagonia.

On 10 September 2019, the song was sung in the UK House of Commons by Plaid Cymru and Welsh Labour members of parliament who were protesting about Brexit and the prorogation controversy.

The Calon Lân Centre is based at Mynyddbach Chapel, the burial place of Daniel James. The chapel and grounds were at the point of dereliction until 2011 but have been restored.

Lyrics
Alternative words in the Welsh version:
 * Verse 1, line 3: Gofyn wyf am fywyd hapus
 * Verse 2, line 2: Chwim adenydd iddo sydd
 * Verse 3, line 2: Esgyn ar adenydd cân
 * Chorus, line 3: Does ond calon lân all ganu