Mr. Conaway had long struggled with a variety of addictions, including one to prescription painkillers. He had admitted to trying to kill himself on a variety of occasions, often by using pills. Family members decided Thursday to have doctors remove the feeding tube and ventilator that had been keeping Mr. Conaway alive, according to reports. He was removed from life support early Friday.
Jeff Conaway was an understudy in the original Broadway production of Grease, Jim Jacobs and Warren Casey's affectionate musical homage to the greasers and bad girls of Rydell High. He eventually graduated to the romantic lead role of Danny Zuko. When it came time to film the musical, however, Mr. Conaway was cast as Danny's more dangerous sidekick, Kenickie, who enjoys a love-hate relationship with Rizzo, the leader of the Pink Ladies. The role of Danny went to John Travolta, another replacement actor from the original cast.
The same year "Grease" came out, 1978, he began a run playing the free-wheeling, womanizing actor Bobby Wheeler in the television series "Taxi." He was nominated for a Golden Globe Award in 1978 for his role.
Mr. Conaway left "Taxi" after the third season, complaining that he had been underused (some reports have him being fired). Thereafter, his career never regained its early momentum. In the 1990s, he found his most high-profile part in years, playing Sergeant Zack Allan on "Babylon 5."
Jeffrey Charles William Michael Conaway was born on Oct. 5, 1950 in New York City. His parents, a struggling actress and an advertising man, divorced when he was a boy. He began acting early on, appearing as a boy in the 1960 Pulitzer Prize-winning play All the Way Home. In later years, Mr. Conaway would describe a horrific childhood, in which he was taunted by bullies and victimized by pedophiles. He said he began taking drugs while a teenager. In 2006, he attempted to rid himself of his dependencies, while simultaneously remaining in the limelight, appearing on "Celebrity Fit Club." But he left the show to go to rehab early in the season. In 2008, he joined "Celebrity Rehab With Dr. Drew." In early 2010, he had a serious fall that left him with a brain hemorrhage, a broken hip and a fractured neck.
Mr. Conaway was married to Rona Newton-John, Olivia's sister, in the early '80s. He is survived by his stepson with her, Emerson.