O'Neill was found unresponsive in his apartment.
Alan O'Neill, the Irish-born actor best known for playing Hugh on the sit FX series Sons of Anarchy, was found dead in his Los Angeles apartment on Wednesday evening. O'Neill's body was discovered by his girlfriend in the hallway of their residence.
The 47-year-old reportedly had a history of heart problems, was a heavy smoker, and also struggled with alcohol abuse.
Timothy Murphy, who appeared alongside O'Neill in Sons of Anarchy, publicly grieved his death, calling the actor a "good friend." Likewise, O'Neill's manager Greg Meyer notes how "he was a great guy who was very funny and engaging as well as a very talented actor. He was also an expert equestrian horse trainer."
Additionally, O'Neill's agent Annette Walsh lamented how she will "personally miss knowing Alan isn’t sharing the planet with us any longer, despite the miles between L.A. and Dublin, Alan was only ever a phone call away."
An autopsy will take place in the near future, although officials are not suspecting any foul play.