Who was William Hasley? Caitlyn Jenner's Friend and Biographer Found Dead on LA's Runyon Canyon Hiking Trail

William Hasley, a well-known Hollywood screenwriter and ghostwriter who co-wrote works with Olympic champion Caitlyn Jenner, the father of Kendall and Kylie Jenner, has passed away at the age of 78.

The veteran collaborator was found dead on Saturday, 6 June 2026, near the Runyon Canyon hiking area in Los Angeles. Local authorities confirmed that emergency services responded to the scene following a fatal medical event, where Hasley was officially identified by emergency personnel.

Emergency Response at Runyon Canyon

The tragedy unfolded on Saturday evening, around 7 p.m., when emergency crews responded to reports of a hiker in distress navigating the loops of Runyon Canyon Park. According to a report by US Weekly, Hasley was walking the trails within the 160-acre nature reserve when the incident occurred.

The Los Angeles Fire Department, per the New York Post, noted that Hasley was discovered in an area north of Nichols Canyon Road, a location famous for its panoramic views of Hollywood.

'LAFD Air Operations lowered rescuers to the patient, and medical treatment was administered,' an LAFD spokesperson said. Despite executing immediate medical interventions to revive the writer, their efforts were unsuccessful, and Hasley was pronounced dead at the scene.

Following the recovery, the Los Angeles County Medical Examiner officially confirmed Hasley's identity. Authorities have not indicated that foul play is suspected, and the case remains under active investigation. Further details surrounding the circumstances of his death, including the official cause of death, have not yet been released.

Who is William Hasley?

William Hasley built a distinguished career as a screenwriter, author, and educator that spanned several decades in the entertainment industry.

Born in Pittsburgh, Pennsylvania, Hasley attended Marshall University, where he competed in football and cross-country before moving to Hollywood to pursue a career in writing. Over the years, he established himself as a respected figure across television, film and publishing, earning recognition both for his creative work and his mentorship of aspiring writers.

Hasley was perhaps best known outside Hollywood for his long-standing friendship and professional collaboration with Caitlyn Jenner. He co-wrote Jenner's 1996 motivational book, Finding the Champion Within, published by Simon & Schuster. Drawing on Jenner's gold medal-winning performance in the 1976 Olympic decathlon, the book explored themes of perseverance, achievement, and personal development.

Legacy in Writing and Education

Throughout his career, Hasley amassed an extensive list of television writing credits. His work included popular series such as The Smurfs, Fat Albert and the Cosby Kids, Murder, She Wrote, Highway to Heaven, Kung Fu, and The Young Riders.

In addition to television, he developed and sold screenplays to major Hollywood studios, including Warner Bros., Universal and 20th Century Fox, building a reputation as a versatile writer capable of working across multiple genres.

Beyond his work in film and television, Hasley dedicated part of his later career to teaching screenwriting through UCLA Extension. In an instructor statement for the university, he wrote: 'As your instructor, my goal is to help you develop your own distinct style into a concise and creative screenplay for today's ever-changing marketplace.'

'Let's turn your dreams into reality. In my class, only you can limit yourself. I hope to form a camaraderie among my students so you will feel safe enough to fall flat on your pages, then pick them up, and improve on what you have already written,' Hasley wrote.

He continued, 'There is nothing more thrilling than touching another with the words you have written. I challenge you to challenge yourself.'