Authorities identify William Hasley, 78, as the hiker found dead on Hollywood’s Runyon Canyon trail on Saturday evening, according to multiple outlets. Hasley is described as a screenwriter and book co-author who worked with Caitlyn Jenner on a motivational book. One account also says he served as a friend and ghostwriter to Jenner. Reporting across sources links Hasley to television and screenwriting work, including credits connected to “The Smurfs.” The Los Angeles Times and other outlets state the death followed a fatal medical emergency while hiking. Details beyond the identification are limited in the provided reports. One outlet further notes that Hasley was previously married to Robin Riker, an actress known for “The Bold and the Beautiful.” Overall, the coverage agrees on the key points: Hasley is identified as the person who died on Runyon Canyon, he was 78, and he had professional ties to Jenner through their shared book project.