Alan O'Neill has passed away at the age of 47, his rep confirms to E! News.
The Los Angeles County Corner tells E! News that the actor (legal name Michael Alan O'Neill) was pronounced dead at a residence in Toluca Lake, Calif. on Wednesday, June 6 at 6 p.m. An autopsy is currently pending.
Law enforcement sources told TMZ that his body was found by his girlfriend. The site also reports that O'Neill had a "history of heart problems and was a heavy smoker."
From 2013 to 2014, O'Neill starred as Hugh on Sons of Anarchy. His last acting credit is listed on IMDB as Captain in the 2016 movie Urge starring Pierce Brosnan.
Prior to his work on Sons of Anarchy, O'Neill starred in the Irish TV show Fair City for six years. His first acting credit was in 1997, playing Capt. Jim Clarke in the TV movie Ballyseedy.
This heartbreaking news comes just about a month after Sons of Anarchy star David Labrava announced the death of his 16-year-old son.