Marc O'Shea was found dead in his home in Annsborough, close to Castlewellan in County Down, on Sunday night.
In his final post on Facebook, Marc spoke bravely about his own battle with mental health problems. "As someone that suffers with mental health issues I think it's disgusting how the Tories and their cronies are destroying what little mental health care there is left," he wrote.
O'Shea also appeared in 'Breakfast on Pluto' and played loyalist paramilitary leader Johnny Adair in Channel Four biopic `Mo'.
O'Shea worked a lot in local theatre and was a strong advocate of social justice campaigns. As one friend told the press, Marc was "totally committed to fighting all forms of discrimination and oppression, an inspiration to all around him".
The tributes have been flowing in since word of his death. "The theatre community in Northern Ireland is having to come to terms with the sudden death of yet another of our friends and colleagues, Marc O'Shea", said producer and director Stephen Beggs.
"Marc was a fine actor and a great friend to many of our members. He will be much missed by everyone who knew and worked with him."
The film director Dudi Appleton worked with Marc on the comedy`The Most Fertile Man in Ireland'. And he describes Marc as "a viciously talented actor and a huge heart".
He say: "He was the soul of the set any time I saw him work. We were shooting one day in Ardmore and I saw Marc in the costume truck. I was pretty sure he wasn't called that day. Turned out he showed up because it was no fun in the hotel on his own.
"He came onto set in a blue camisole, wig and makeup and announced he was Tara Lynne O’Neill’s body double. Hard not to cry thinking about the times Marc kept us laughing.
"God bless you (wee) big man."
While Kabosh Theatre Company stated that they are all "very sorry to hear of the sudden death of actor Marc O’Shea", adding: "We had some craic working with him on the Referee project for the Electoral Commission in Belfast and Derry. He'll be sorely missed. Rest easy."