Val Kilmer had been dogged by rumors that he was a Hollywood diva and a pain to work with … but one costar and friend tells TMZ that’s a total crock.

Danny Trejo, who was among the star-studded cast of “Heat” with Val, tells TMZ … Val got a bad rap for being difficult to work with — but the icon wasn’t high-maintenance — he was a “perfectionist.” There’s a big difference, DT makes clear.

As you sadly know … the legendary actor died Tuesday at the age of 65 — his death sending shockwaves through Hollywood as most didn’t realize his health had deteriorated so severely.

Highlighting what a thoughtful dude Val actually was, Danny shared one of his favorite memories from their time on “Heat” — and it’s kinda a tear-jerker now.

One day, Val showed up to set wearing a fancy and obviously very expensive leather jacket — and Danny commented on how much he liked it. The next day, there was one in his trailer … a gift from Val.

Danny says the only issue he ever had with Val … his pal didn’t get nominated for an Oscar as Doc Holliday in “Tombstone.”

Christina Fulton is another one of Val Kilmer’s heartbroken former costars … speaking to us about her favorite memories with him.

TMZ caught up with Christina outside the courthouse in Downtown L.A. Tuesday during her legal battle with her son — and she essentially spoke to the late actor through our camera, thanking him for being kind and generous to her on set for their ’91 movie “The Doors” when she was a new actress in L.A.

Catch the clip — Christina shares more personal words about the lasting impact Val had on her, and it’s truly heartbreaking … especially since they kept in contact over the years.

A 17-year-old has been charged with one count of murder … after he allegedly stabbed another 17-year-old during an altercation at a high school track meet in Texas on Wednesday.

Frisco Police said the incident took place at around 10 AM at the Frisco Independent School District’s Kuykendall Stadium … where several students were competing in the University Interscholastic League’s (UIL) District 11-5A championship.

According to cops, Frisco Centennial High School’s Karmelo Anthony killed Frisco Memorial High School’s Austin Metcalf following a dispute at the event.

“The Frisco Police Department grieves with all those affected by this devastating loss and extends its deepest condolences to the victim’s family, students, and staff who are experiencing unimaginable pain,” the Frisco PD said in a statement. “The department is collaborating with the Frisco Independent School District and will continue to provide any support they need during this incredibly difficult time.”

Metcalf described himself as a 6-foot, 220-pound football player with a 3.97 GPA on his X page. His last post on the social media app stated, “Faith that god got me and my work will pay off.”

Anthony, meanwhile, described himself as a 5-foot-10, 175-pound footballer with a 3.7 GPA.