Ommadawn is the third studio album by English musician, multi-instrumentalist and songwriter Mike Oldfield, released in November 1975 on Virgin Records.

The song that concludes "Ommadawn (Part Two)", entitled "On Horseback", was released as a single in November 1975 with Oldfield's non-album track "In Dulci Jubilo".

In 2010, Mercury Records issued a remastered edition containing new stereo and 5.1 surround sound mixes by Oldfield and extra material.

By the end of 1974, Oldfield had been propelled to worldwide fame by the unexpected critical and commercial success of his debut studio album, Tubular Bells (1973).

[7] Oldfield initially felt depressed at having to start again, but then noticed that "something clicked inside of me" and realised that his previous takes had been good practice for the final ones.

[5] Excerpts from the scrapped version were used in Oldfield's interview on Tony Palmer's documentary series All You Need is Love[8] and in the 1977 film Reflection.

[6] The latter ends with a song entitled "On Horseback", written by Oldfield and lyrics by Oldfield and William Murray and, while it was banded separately on vinyl from "Ommadawn (Part Two)", it was only referred to as "the horse song" in the liner notes, only properly credited by name on its accompanying single and on remastered copies of the album released from the 2010s onward.

As the album, like many of Oldfield's at that time, did not have a lyrics sheet, attempts were made to decipher the lyrics; one such attempt which has persisted over the years was: Ab yul ann idyad awt En yab na log a toc na awd Taw may on omma dawn ekyowl Omma dawn ekyowl These lyrics are written in an English-based respelling system, but all four lines are easily recognisable as an Irish translation of the English words, although the first two lines have undergone a process of partial scrambling: combinations of vowel + semivowel are kept intact, but otherwise the lines are written backwards (so, e.g., idyad awt corresponds to taw daydi) and some word spaces have been changed.

Prior to his autobiography, Oldfield had denied this meaning of ommadawn, calling it a nonsense word, apparently as a ruse to enhance the mystery of his music.

Paul Stump, in his 1997 History of Progressive Rock, said that "the technically and emotionally polymathic Ommadawn operates on several levels at once, not least because Oldfield states two themes rather than one near the beginning and doesn't try to develop them sequentially over fifty minutes but allows each its space to breathe and display itself, both singularly and with the other."

A small portion of Part One was used as the theme to the children's TV show Jackanory on occasions when John Grant narrated his Littlenose stories.

In June 2010, Ommadawn was reissued as Deluxe Edition by Mercury Records as part of Oldfield's remastered album series for the label.