Caitlyn Jenner’s biographer William Hasley found dead on LA’s Runyon Canyon hiking trail

Caitlyn Jenner’s friend and ghostwriter William Hasley has been identified as the Runyon Canyon hiker found dead last Saturday.

The 78-year-old, who was also a screenwriter and former husband of actress Robin Riker, penned Jenner’s book “Finding the Champion Within” for Simon & Schuster. 

The 1996 self-help book described Jenner’s athletic accomplishments and aimed to use a 10-step program to “reboot” the readers’ life.

Hasley said in his biography they became “fast friends” while he was working on an Olympics-related project before the former athlete commissioned him to write the book.

The writer was found in an area near Runyon Canyon at about 7:05 p.m. on Saturday, the Los Angeles Fire Department said. Air rescuers attempted to save the man but were unsuccessful.

A neighbor near his home, located near Runyon Canyon, expressed regret about his lonely death. 

“I just saw him on Saturday carrying groceries,” the neighbor told The Post. “It’s very sad he had to die all alone like that.”

Temperatures in the Los Angeles area were cool, in the mid-to-low 60s, around the time of Hasley’s death. It was not clear how he died.

“LAFD Air Operations lowered rescuers to the patient, and medical treatment was administered,” an LAFD spokesperson said. Officials pronounced Hasley dead at the scene.

The Hollywood screenwriter’s television credits include Swift Justice; Ghost Stories; Murder, She Wrote; Kung Fu; Young Riders; and Highway to Heaven.

He also wrote screenplays for Universal Pictures, Warner Brothers, and 20th Century Fox, among others.

His actress ex-wife, Riker, became a star on the Showtime sitcom “Brothers” as Kelly Hall in the 1980s. She became a television regular for the next decade, and saw her most recent notable credit on the long-running “The Bold and the Beautiful” show as Beth Logan.

Hasley was also an instructor in screenwriting at UCLA. He said he helped students “develop your own distinct style into a concise and creative screenplay for today’s ever-changing marketplace.” 

His biography described him as an environmentalist who also enjoyed riding horses, sports, teaching, and volunteering.

“When Will isn’t meeting a deadline, you’ll most likely find him fighting City Hall over an environmental issue, writing an article, teaching a writing class at UCLA, volunteering in a soup kitchen, or speaking to a youth organization,” the biography said. “Will’s a great sports enthusiast. He’s often playing in a Celebrity Golf Tournament, Showbiz Softball League, or riding horses with the infamous Hole in the Wall Gang.”

The Los Angeles County Medical Examiner’s Office has not released a cause of death, deferring any official determination.

The California Post reached out to reps for Jenner and UCLA for comment.

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