Or maybe, if you’re a newer fan, you know the actor from his recent supporting TV roles on the HBO series Succession, the Netflix drama You, and Amazon’s Mozart in the Jungle. But what you may not know is that the late actor was a mainstay of the New York theater scene. He was a regular on stage at Playwrights Horizons, where he recently starred in Rancho Viejo and Fern Hill at 59E59 Theaters. Recent Broadway credits include The Assembled Parties, Twelve Angry Men, two turns in Gore Vidal’s The Best Man and Neil Simon’s Lost in Yonkers. Blum was also a SAG-AFTRA board member from 2007 to 2013.

Playwrights Horizons tweeted in memory of Blum this month.

Soon, many other well known names came forward to remember the actor. Rebecca Damon, executive vice president and New York president of the Screen Actors Guild-American Federation of Television and Radio Artists (SAG-AFTRA) labor union called a “tireless advocate” for fellow performers, according to CNN. She went on to say, “I always appreciated Mark’s clear perception of complex situations. He always spoke the truth and did a great service in informing members of our community about the ins and outs of the union whenever he had the opportunity.”

Actor Zach Braff said he “could not have been a kinder human being” and praised his “wonderful” acting. Similarly, Cynthia Nixon called his performances “unfailingly deep, subtle, hilarious and moving in equal measure.”

Even Madonna remembered her former co-star in a heartfelt Instagram post in which she called Blum “a remarkable human” and urged people to continue to self-isolate to slow the spread of the virus.

Blum is one of many New York theater-makers to have contracted the virus. The list also includes actors Gavin Creel, Aaron Tveit, Laura Bell Bundy, and composer David Bryan. Tragically, COVID-19 also claimed the life of four-time Tony-winning playwright Terrence McNally.

Blum was 69 when he died and leaves behind his wife Janet Zarish.