Pádraig Duggan, one of the founding members of Irish folk group Clannad, has died aged 67.
Taking their name from the Irish word for family, the band consisted of Ciarán, Pól and Moya Brennan and their twin uncles Noel and Pádraig Duggan.
They achieved mainstream success in the 1980s with the themes to TV shows Harry's Game and Robin of Sherwood.
Duggan, who played guitar and mandolin, died in a Dublin hospital on Tuesday morning, following a recurring illness.
"My dear uncle and Clannad member Pádraig Duggan passed away peacefully this morning," wrote Moya Brennan on Twitter. "Rest in Peace, Pádraig."
Clannad successfully bridged traditional Celtic music and pop, and became the first band to sing in Irish on Top of the Pops in 1982.
They began performing in Leo's Tavern, a family-owned pub in Donegal, north west Ireland, before winning the Letterkenny Folk Festival in 1973.
The prize included a recording contract with Phillips, and they decided to pursue music full time, initially finding success in Europe.
Steeped in the history and landscape of Ireland, their haunting, ethereal music took near-forgotten folk songs and framed them with new arrangements, decorated with the band's unique close harmonies.
Their younger sister was recruited to the band in the late 1970s and went on to have international solo success as Enya.
Clannad's crossover came in 1982 when the band were asked to record the theme for ITV mini-series Harry's Game, set among the sectarian violence in Northern Ireland.
Released as a single, the song reached number five in the UK charts and won the band an Ivor Novello songwriting award. It was also played as the entry music on every night of U2's War Tour in 1983 and propelled Clannad's album, The Magical Ring, into the UK top 40.
Bono later appeared on the band's hit single In a Lifetime, while Clannad's soundtrack for TV drama Robin Of Sherwood won the band a Bafta.
The band continued to release albums into the 1990s, embracing a more rock-orientated sound without alienating their core audience.
Their US career received a boost in 1993 when Volkswagen used the Theme From Harry's Game in a television commercial. The German company found their phone lines buzzing, not because people wanted to buy a car, but because they wanted to know more about the music.
The exposure gave the band their first US chart entry, and, in the same year, they contributed a track to the Oscar-winning drama The Last of the Mohicans, painstakingly researching the Mohican tribe to write the lyrics in their near-extinct language.
In 1997, they released their 15th album, Landmarks, winning their first ever Grammy Award, for best New Age recording - but it also marked the beginning of a long hiatus for the band.
During that time, Pádraig and Noel released their own album, Rubicon, which featured a new version of Liza - the song with which Clannad had won the Letterkenny Folk Festival more than 30 years earlier.
"I actually wrote it up on the roof of Leo's Tavern," he recalled. "I was up there for some reason with my guitar. It is an upbeat pop song, I suppose I was influenced by bands such as The Beatles.
"It was a unique song at the time: a pop song in Gaelic! It proved popular in the local schools [and] the young people seemed to adopt it."
The song is still used to teach children Gaelic in schools across Ireland.
Clannad reformed in 2012, touring Europe and picking up the lifetime achievement prize at BBC Radio 2's Folk Awards in 2014.
Pádraig's death comes just weeks after Leo Brennan, father of Ciarán, Pól and Moya and owner of Leo's Tavern, died at the age of 90.
The musician is survived by his wife Jan. A funeral will be held in St Mary's Church, Derrybeg, on Thursday.