A New Jersey native, Blum also had a role in 1986’s “Crocodile Dundee” and appearances on a string of TV series, including “NYPD Blue,” “The Sopranos,” “The West Wing” and recently the cult hit “You,” playing bookseller Mr. Mooney.

“With love and heavy hearts, Playwrights Horizons pays tribute to Mark Blum, a dear longtime friend and a consummate artist who passed this week,” the off-Broadway theater tweeted. “Thank you, Mark, for all you brought to our theater, and to theaters and audiences across the world. We will miss you.”

His onscreen wife in “Susan,” Rosanna Arquette, also expressed her sadness at Blum’s passing, after being told of it by author Sharon Waxman.

“Sharon Waxman informed me of this very very hard news today,” wrote Arquette. “I’m so deeply sad for his family and for his fans. he was a wonderful actor and a very good and kind man. May you Rest In Peace and power mark. God bless you.”

Blum, a University of Pennsylvania graduate, is recalled by his colleagues and critics for the intensely high quality of his work. He was particularly beloved in the theater community.

“There are actors whose names appear in the announcement of a play, and you instantly think, without knowing any details: This will be work worth seeing,” Washington Post theater critic Peter Marks posted. “Mark Blum was of that wonderful caliber. Made me believe, every time I saw him. It’s terrible to read of his death.”

Playwright Christopher Shinn also took to Twitter to salute Blum’s life and kindness.

“In 2011 Mark Blum starred in my play Picked @vineyardtheatre, in a tricky role — a narcissistic filmmaker whose more human instincts collide with the desire to protect himself from emotional risk,” Shinn wrote. “Mark’s performance took huge risks. He was magnificent. And the kindest man. RIP.”

Blum leaves behind his wife and fellow actor, Janet Zarish, also 69, whose credentials include guest appearances on “Law & Order,” “Seinfeld” and “Blue Bloods.”