Mark Sheehan, who played guitar for the Irish pop band The Script, died in the hospital after a short sickness at age 46.
In 2001, Sheehan, the lead singer Danny O'Donoghue, and the guitarist Glen Power put together a band.
In a message on their social media pages, the band said, "Much loved husband, father, brother, bandmate, and friend Mark Sheehan died today in the hospital after a short illness.
Sheehan was married to Reena Sheehan, whom he met when she was working as a session singer. Together they had three children.
Last year, when the guitarist missed the US part of the band's tour, O'Donoghue told Sunday World that Sheehan had taken a break to spend time with his family.
He also said that the group agreed with Sheehan's choice and that they were "a band of brothers" who "stick together no matter what."
Later, Sheehan got back together with his friends and played a few shows in Ireland. This summer, the group will be opening for US singer Pink at shows in the UK and Europe.
From 2010 to 2019, the band had more UK No. 1 records than anyone else from Ireland.