TMZ reports, Legeno's body was found by two hikers in a remote part of the trail on Sunday. After the pair alerted authorities about the body, a California Highway Patrol helicopter was called in to remove it.
The Inyo County Sheriff's Department said the actor died of heat related issues and may have been dead for three or four days by the time his body was found. The Death Valley's website, describes the park as a hot, dry and low "land of extremes." Temperatures in the summer reportedly go over 120 degrees.
Legeno, 50, reprised the role of werewolf Fenrir Greyback in the sixth, seventh and eighth Harry Potter films. He also had roles in Hollywood blockbusters Snatch and Snow White and the Huntsman and is set to appear in the upcoming 2014 films: The Last Knights, Sword of Vengeance and Petroleum Spirit.
The actor is survived by a daughter who is in her 20s.