At this point in time, the circumstances surrounding his death are unclear, however, one Twitter user claimed she had seen the late actor recently, revealing he relied on crutches to walk and "looked to be in a lot of pain".
Most viewers remember Karl from the first season of the hit BBC series 'Peaky Blinders'. He's also known for playing Robbie on the RTE soap 'Fair City'.
Tributes from his co-stars and former colleagues have since flooded in, with Irish actor and comedian Chris O'Dowd offering his condolences.
"So sorry to hear about the passing of Karl. The kind of actor you'd always be happy to see pop up on the screen," he wrote on social media. "The kind of fella you'd always be delighted to bump into in the street."
'Fair City' co-star Eric Lalor also sent his condolences, saying he was “absolutely stunned and heartbroken” to hear the news of his passing.
“A hugely gifted actor and a really great friend, I will miss him so much. Thinking of his gorgeous family, may he Rest In Peace,” he wrote.