Netflix began streaming a compelling new documentary, Sly, on November 3, which delves deep into the extraordinary life and career of iconic actor Sylvester Stallone. The feature-length documentary explores Stallone's professional accomplishments and the personal challenges he's faced, particularly the heart-wrenching loss of his firstborn son, Sage Stallone, who tragically passed away in 2012. Despite his untimely passing, Sage had already begun to establish himself in the film world. By the age of 30, he had not only inherited his father's talent but had also garnered experience as an actor, producer, and director. Who was Sage Stallone? Instagram Sylvester Stallone welcomed Sage during his first marriage with Sasha Czack, which lasted from 1974 to 1985. As the late star matured, he followed in his father's illustrious footsteps and made his mark on the silver screen by starring in the movie Rocky V, where he played Rocky Balboa's son. RELATED: Meet All Five Of The Wild Children Of Sylvester Stallone His acting career continued to flourish with appearances in another Stallone classic, Demolition Man, and in the action-adventure film Daylight. Not confining himself solely to acting, Sage also ventured into the realm of filmmaking, directing and producing a documentary titled Alan Yates Uncovered as well as the short film Vic. He also took on the role of executive producer with the crime drama Gone with the Pope. Sage was briefly married to American actress and model Starlin Wright from 2007 to 2008, however the couple did not welcome any children together. ROCKY V, Sylvester Stallone, Sage Stallone, 1990, (c)United Artists/courtesy Everett Collection How did Sage Stallone die? Sage passed away in July 2012 at the age of 36 in his Los Angeles home. According to a toxicology report, his cause of death was attributed to coronary artery disease, which ultimately resulted in a fatal heart attack. The report indicated that no substances other than over-the-counter painkiller medication were found in his system at the time of his death. Instagram His mother also corroborated the toxicology report by stating that Sage was prescribed painkillers to manage post-surgical discomfort from a dental surgery, which necessitated the removal of five of his teeth.