Mel Brooks was with Carl Reiner when he collapsed and died

Friends until the end. 

In the upcoming HBO documentary, “Mel Brooks: The 99 Year Old Man!,” the comedy legend reveals that he was with his best friend, Carl Reiner, when the latter passed away. 

“Mel was there when my dad died,” Carl’s son, Rob Reiner, said in an interview for the documentary, before his own tragic murder at 78 on Dec. 14. 

Talking about his father Carl, Rob added, “He just collapsed in the bathroom, and Mel came back and realized, ‘Uh oh, something’s wrong.’”

Carl “died right after that” from a heart attack, Rob explained. 

Brooks, 99, explained onscreen, “I just didn’t want him to go. I just couldn’t — I wouldn’t accept it. I loved him so much.”

Carl died at 98 in 2020. 

Brooks and Carl were lifelong best friends, collaborating on projects like “The 2000 Year Old Man.” 

After Brook’s second wife, Anne Bancroft, died in 2005, and Carl’s wife Estelle Reiner died in 2008, the two men ate dinner together nearly every night. 

“I was still hoping that they would put the stuff on him and boom, get him up. I kept yelling at them, ‘Keep it up, keep it up,’ and they thought I was crazy after an hour of yelling,” Brooks recalled, about Carl’s death. 

Onscreen in the documentary, before his own death, Rob recalled about Brooks, “After my father died, he would come to the house, sit there, watch television and have dinner, and he did that for months. And he told us, the family, he said, ‘Let me know when you’re gonna sell the house.’ ”

“The Princess Bride” director added, “I said, ‘Maybe it would be better to stage the house with you in it.… It’ll up the value. You get Mel Brooks sitting here.’ ”

Directed by Judd Apatow and Michael Bonfiglio, “Mel Brooks: The 99 Year Old Man!” covers the comedy legend’s life and career, featuring interviews with Brooks, Reiner, and other famous comedians such as Adam Sandler, Jerry Seinfeld, Dave Chapelle, and Ben Stiller. 

The doc covers Brooks’ comedy origins, his marriages to Florence Baum and Anne Bancroft, and his reflections on his career highlights such as “Young Frankenstein,” “The Producers,” and “Blazing Saddles.”

Onscreen, Rob added, “He was that close to my dad, where he kept, he wanted to be close to him even when my dad was gone. I always thought even though Mel was only like four years younger than my dad, I think he looked to my dad as a father figure.”

“Mel Brooks: The 99 Year Old Man,” premieres Thurs. Jan. 22 (8 p.m.) on HBO.