News of Blum's death was confirmed by Playwrights Horizons theatre:
With love and heavy hearts, Playwrights Horizons pays tribute to Mark Blum, a dear longtime friend and a consummate artist who passed this week. Thank you, Mark, for all you brought to our theater, and to theaters and audiences across the world. We will miss you. pic.twitter.com/NMVZFB5hPb— Playwrights Horizons (@phnyc) March 26, 2020
Blum was perhaps best known for his role in Desperately Seeking Susan. More recently, he had recurring parts in Amazon's Mozart in the Jungle and Netflix's You. Over the years, he appeared in television shows including Roseanne, Wings, Frasier, NYPD Blue, The Sopranos, The West Wing and Law & Order. He also played a newspaper editor in Crocodile Dundee.
Blum is survived by his wife Janet Zarish.