O’Neill’s body was discovered by his girlfriend in the hallway of their Los Angeles apartment on Wednesday night.
Local police said foul play is being ruled out as a cause of death. According to the website TMZ who first broke the news, Alan had a history of chronic heart problems; they also claimed he was a heavy smoker and drinker.
Paying tribute this morning,O’Neill’s casting agent Annette Walsh said: “It’s with great sadness I can confirm the passing of Alan O’Neill, a brilliant, funny and kind human being. My thoughts are with his partner, children, family and friends at this time.”
Sons of Anarchy star Timothy V Murphy tweeted this morning: “My good friend Alan O’Neill died today… we worked together on the Sons of Anarchy… My condolences to his family.”
'Fair City' actress Jenny Dixon also took to Twitter this morning to pay tribute to Alan. She wrote: "One of the first films I did and a privilege to act across from Alan O’Neill. A great friend who taught me so much. Thank you for your kindness. So very sorry to hear of your passing. A great man, sadly missed. My thoughts and prayers to you and to your family.”
While a spokesperson for 'Fair City' said: "All of us are so deeply saddened to hear this terribly sad news. Alan was a breath of fresh air on set, always full of energy and passion. He was an absolute joy to work with.
"During his time on Fair City his contribution to both his character and the production was always peppered with an enthusiasm that became infectious, he will be missed greatly by all in Carrigstown."

One of the first films I did & a privilege to act across from @AlanONeill19 .A great friend who taught me so much. Thank you for your kindness. So very sorry to hear of your passing. A great man, sadly missed. My thoughts & prayers to you & to your family?? pic.twitter.com/Kygj7pybWo

— Jenny Dixon (@JennyleeDixon) June 7, 2018