Ellen Lubin Sanitsky, Post's manager, confirmed the news to EW. Post had faced cancer for almost four years.
Presley Ann/Patrick McMullan via Getty Markie Post
The actress was well-known for playing public defender Christine Sullivan, on more than seven seasons of the comedy Night Court, alongside the late Harry Anderson (Judge Harry Stone), and Charles Robison (Mac), who passed away last month, John Laroquette (prosecutor Dan Fielding), Richard Moll (Bull), and Marsha Warfield (Roz).
She joined the series after starring in the Lee Majors-fronted The Fall Guy from 1982-1985.
Post had a lengthy television career, beginning in the late 1970s. Among the notable shows she guest starred in were CHiPs (1979), The Incredible Hulk (1979), Buck Rogers in the 25th Century (1979), Eight Is Enough (1980), The Greatest American Hero (1981), The Love Boat (1982), Cheers (1983), and Fantasy Island (1984). More recently, she played Barbara "Bunny" Fletcher on several episodes of NBC's Chicago P.D. – the troubled mother of Sophia Bush's former character, Erin Lindsay.
Bush expressed her grief over the loss of her former costar, whom she called "a light," on Twitter on Sunday.
"I'm just heartbroken at the news of Markie's passing … she was a rock. A light. A great friend and a phenomenal scene partner. She brought sunshine everywhere she went. Prayers," Bush tweeted.
I’m just heartbroken at the news of Markie’s passing … she was a rock. A light. A great friend and a phenomenal scene partner. She brought sunshine everywhere she went. Prayers. https://t.co/D6mAqEnzBJ pic.twitter.com/Aj9uZG8vPX
— Sophia Bush (@SophiaBush) August 8, 2021
Bush's One Tree Hill costar Hilarie Burton, who also played Post's daughter (in the 2013 film Christmas on the Bayou) also shared an emotional goodbye.
"Devastated just isn't a strong enough word. To know Markie Post was to fall head over heels in love with her," she wrote alongside shots from the film as well as a Mother's Day exchange the two women shared.
Ed Asner also posted a tribute to his former Hearts Afire costar on Twitter, writing, "I am devastated to hear of the passing of my friend Markie Post. She was a true talent. We did Hearts Afire together and to work with her and John was a gift. F&@k Cancer! #MarkiePost."
I am devastated to hear of the passing of my friend Markie Post. She was a true talent. We did Hearts Afire together and to work with her and John was a gift. F&@k Cancer! #MarkiePost pic.twitter.com/b34yR5C5Th
— Ed Asner (@TheOnlyEdAsner) August 8, 2021
Post opened up about her career after entertainment journalist Fred Topel asked if she visualized such success back in a 2012 interview for Patch.
"I was not a big visualizer. I was sort of a leap in and see what happens kind of person," she said at the time.
"And in the beginning, I would do everything," Post continued. "I would do Love Boat and Barnaby Jones. I would be grateful for it. Buck Rogers, all the Aaron Spelling stuff, everything and just be so happy. And then I began to be the sort of go-to person, the girl who was on the episodic TV and then got offered a series, my first one. Then I'd narrow this stuff down and began to do that. And then it gets to be where you sort of have to be more selective and less stuff is coming at you but more quality stuff is coming at you. So I think that was unconscious, I think it was maybe good representation. I'm a person who loves to work so I think sort of naturally in a way it happens if you get traction in the beginning which I did. I was so lucky."
EW has reached out to Post's rep for comment.