Ex-NBA player Jason Collins — the league’s first openly gay player — just opened up on his serious health battle … revealing he was diagnosed with Stage 4 glioblastoma, “one of the deadliest forms” of brain cancer.

Collins, who announced he had a brain tumor earlier this year, detailed his journey in an interview with ESPN‘s Ramona Shelburne … saying he first noticed symptoms back in August.

“Imagine a monster with tentacles spreading across the underside of my brain the width of a baseball,” Collins said … adding it’s impossible to fully resect the mass without coming out of the procedure “different.”

“My glio is extraordinary for all the wrong reasons, and is ‘wild type’ — it has all these mutations that make it even more deadly and difficult to treat.”

But Collins fought — starting with medication, then radiation and chemotherapy … and it worked. He said he slowly started to come out of his fog.

Even with all the treatment, Collins said the average prognosis is 11-14 months.

“If that’s all the time I have left, I’d rather spend it trying a course of treatment that might one day be a new standard of care for everyone.”

Tyler Robinson — the 22-year-old man who prosecutors say murdered Charlie Kirk — made his first in-person court appearance Thursday.

Robinson’s father, mother and brother were present as both sides were able to come to an agreement with regard to the degree of media access granted throughout the ongoing court proceedings.

Robinson previously appeared in court a few days after the shooting, via video call. Today, he sat in the Provo, Utah courtroom wearing street clothes … a privilege his lawyers fought for in a motion to ditch the jail garb.

As you know, Kirk was shot and killed on the Utah Valley University campus in Orem, UT in September … and, after an extensive manhunt, Robinson turned himself in to authorities.

Robinson allegedly confessed to the crime to his father, who then told a youth pastor who happens to work with the U.S. Marshals Service. Robinson ultimately surrendered at Utah’s Washington County Sheriff’s Office, around 10 PM on Sept. 11, the day after the shooting.

Utah prosecutors charged Robinson with aggravated murder, felony discharge of a firearm causing serious bodily injury, and obstruction of justice.

Ethan Hawke is defending actor Paul Dano after Quentin Tarantino absolutely trashed PD’s acting … finding the silver lining for his unjustly maligned pal!

Check it out … on Thursday’s episode of “The Joe Rogan Experience,” the “Blue Moon” star reacted to Quentin’s out-of-nowhere sharp criticism of Dano — telling host Joe Rogan Paul probably didn’t realize just how many people love his work.

ICYMI … last week, Tarantino trashed Dano‘s work, saying the 2007 flick “There Will Be Blood” would have been great without one “big giant flaw” — Dano’s portrayal of the character Eli Sunday.

On Rogan’s podcast, Ethan reasons further … “Anybody that knows Quentin knows he just talks, talks, talks, talks, talk, talks, talks,” while “anybody that knows Paul knows he’s a great, world-class human being.”

And if it helps … Paul wasn’t the only one Quentin decided to publicly rip on — he also said he doesn’t “care” for Matthew Lillard and “can’t stand” Owen Wilson as an actor.