Spokeswoman Kathryn Boole says the 60-year-old actor died Friday morning at the Encino Tarzana Medical Center, where he had been hospitalized in a coma since May 11. His manager, Phil Brock, has said Conaway had tried to treat himself with pain pills and cold medicine while in weakened health.
The actor had long battled drug and alcohol addiction, which he blamed in part on back problems and repeated surgeries. The reality series "Celebrity Rehab" showed his struggle for sobriety.
Conaway played high school bad-boy Kenickie in the 1978 movie "Grease" and appeared in the Broadway version of the musical.
He played struggling actor Bobby in the sitcom "Taxi" from 1978 to 1981.