Jeff Conaway: Actor best known as Kenickie in 'Grease' and Bobby Wheeler in 'Taxi'

Starring as the swaggering, leather jacket-wearing heartthrob Kenickie, alongside John Travolta, in the film version of the hit musical Grease brought Jeff Conaway global fame. Cinema audiences were quick to learn of Kenickie's two biggest loves – fast motors and fast women – in an early scene where he has sex in the back of his car with his girlfriend, Rizzo (Stockard Channing). Kenickie is a leading light in the high-school T-Birds gang of greasers and sidekick to Danny Zuko (Travolta), whose rekindling of a summer romance with Sandy Olsen (Olivia Newton-John) is the central story in the 1978 film. Conaway had already played Danny in the stage musical on Broadway but had to make way on screen for Travolta, who was hot property following his starring role in the film Saturday Night Fever.

But Conaway himself became a star as a result of the film and, shortly after Grease's release in the United States, he was playing the dim-witted, out-of-work actor Bobby Wheeler, driving for New York's Sunshine Cab Company, in the television sitcom Taxi (1978-82). The programme also featured Danny DeVito as the firm's heartless boss, Louie de Palma, and Judd Hirsch as the compassionate, leading cabbie, Alex Rieger. Bobby's rare acting opportunities were always eventually thwarted and his pretensions were a regular target for Louie.

Although rarely out of work himself in the decades following his two biggest successes, Conaway constantly battled substance and alcohol abuse, and went into rehabilitation more than once. In 2008, he was featured in the television series Celebrity Rehab with Dr Drew and admitted he had been a drug addict since his teenage years and had problems staying off the painkillers he was prescribed for a serious back problem. On a radio show in the same year, he claimed to have attempted suicide 21 times through overdoses. Last year, Conaway had a fall in his home, breaking a hip, arm and his neck, as well as suffering a brain haemorrhage. He died last month, two weeks after being found there unconscious, believed to be as a result of taking prescribed medication.

Born in New York in 1950, Conaway was 10 when he acted alongside Colleen Dewhurst and Lillian Gish on Broadway in All the Way Home (Belasco Theatre, 1960-61). He was cast after his mother, Helen, an actor with the stage name Mary Ann Brooks, took him along to her audition for another part that she failed to land. He worked as a child model and appeared in commercials, attended Quintano's School for Young Professionals and was lead singer and guitarist with the rock band 3 .

Then, he enrolled at North Carolina School of the Arts, before taking acting and dancing classes at New York University. While there, Conaway made his film début as a drug addict in Jennifer on My Mind (1971), but he left university three months before graduation when he was offered the chance to understudy the male characters in the stage version of Grease.

The actor also appeared in episodes of popular television series such as Happy Days (1975, 1976), Mary Tyler Moore (1976) and Kojak (1978). Following the film adaptation of Grease and his run in Taxi, he struggled to get fulfilling roles. He spent most of the 1980s and 1990s in TV films and straight-to-video features. There was a comeback of sorts when he was cast as the photographer Mick Savage in the daytime soap opera The Bold and the Beautiful (1989-90) and he had a longer run as the security chief Zack Allan in the sci-fi series Babylon 5 (1994-98).

In between, he was arrested for drink-driving after colliding with a cyclist and forced to attend Alcoholics Anonymous sessions for three years. Then, in 1997, he played the disc jockey Vince Fontaine in the Broadway revival of Grease. A new century simply brought further forgettable film and television roles and, by 1996, when he appeared in Celebrity Fit Club USA – which he had to leave for rehabilitation – he had become fodder for reality television producers.

Conaway's early, brief marriage to a dancer at the age of 21 was annulled. His subsequent marriages, to Rona Newton-John (1980-85, the sister of Olivia) and Kerri Young, in 1990, both ended in divorce. He is survived by the singer Vikki Lizzi, his partner since 2005.

Jeffrey Charles William Michael Conaway, actor: born New York City 5 October 1950; married three times; died Los Angeles 27 May 2011.