Thousands of tributes have since poured in, with many of his former co-stars taking to social media to honour him.
"I am so devastated by Mark Blum’s passing," said Cynthia Nixon. "His performances in the dozens of plays I saw him in were unfailingly deep, subtle, hilarious and moving in equal measure. Seeing his name in the Playbill always meant you were in for a treat. Also just one of the loveliest humans ever."
Playwright Jack Canfora— who worked closely with Mark in the theatre— also wrote: "He was one of the most respected actors in New York: a beacon of fierce intelligence, dry wit & deep kindness on stage and off. A tragic loss."
Rosanna Arquette, who starred in 'Desperately Seeking Susan' with Mark took to Twitter to express her sadness, admitting the loss was "very very very" hard for her to process.
“I’m so deeply sad for his family and for his fans,” she said. "He was a wonderful actor and a very good and kind man. May you Rest In Peace and power mark. God bless you."
The New Jersey-born entertainer's Broadway career spanned nearly 40 years, with Mark also having more than 80 film credits to his name. He began his career working in theatre and eventually moved on to the big screen, making a name for himself as a rising star after appearing in 1985’s 'Desperately Seeking Susan'. He also went on to star in 1986’s 'Crocodile Dundee'. On television, Mark scored guest parts in shows such as: 'St. Elsewhere', 'Miami Vice', 'Roseanne', 'Wings, Frasier', 'The Sopranos', 'The West Wing', 'The Practice', 'Judging Amy', 'The Good Wife', 'Law and Order', 'The Blacklist', 'Difficult People', 'Elementary and Billions'.
Mark is survived by his wife, Janet Zarish. Rest in peace.