"Black Is the Colour (of My True Love's Hair)" (Roud 3103) is a traditional folk song first known in the Appalachian Mountains region of the United States in 1915, but most probably originating from Scotland, as attributed to the reference to the Clyde in the song's lyrics. The musicologist Alan Lomax supported this Scottish origin, saying that the song was an American "re-make of British materials." The first recording was made by Mrs. Lizzie Roberts in 1916 as "Black Is The Colour".

Many different versions of this song exist, some addressed to females and others addressed to males, as well as other differences:

...like some rosy fair... or ...like a rose so fair...
...the prettiest face and the neatest hands... or ...the sweetest face and the gentlest hands...
...still I hope the time will come... or ...some times I whish the day will come...
...you and I shall be as one... or ...s/he and I can be as one...
These words are set to two distinct melodies, one of which is traditional and the other was written by the Kentucky folk singer and composer John Jacob Niles. Niles recalled that his father thought the traditional melody was "downright terrible", so he wrote "a new tune, ending it in a nice modal manner." This melody was used in the Folk Songs song cycle by Luciano Berio.

While it is unclear which version should be considered "original", it is believed that originally the song was addressed to a woman, with the male-addressed version made popular by Nina Simone in the middle of the 20th century.

The song has become a part of the traditional repertory of Celtic music artists.

In the 1960s, Patty Waters sang an extended version an ESP record which veered towards the avant garde and extremes of vocal improvisation, standing as a landmark in the use of folk tunes as a starting point to other musical areas.