'', In 1975, Palillo was cast as Arnold Horshack, one of the misfit "sweathogs" in the high school sitcom
Welcome Back, Kotter, whose antics made him one of the standout characters of the series. In the last season of the series, a backdoor pilot episode for a spin-off series featuring Horshack was produced, but the series was not developed. Following
Kotter, Palillo appeared in leading and supporting roles in various television series and films. He voiced characters on such animated series as
Laverne & Shirley in the Army,
Darkwing Duck, and
Rubik, the Amazing Cube, in which he played the lead character. In 1996, Palillo played himself in several episodes of the television sitcom
Ellen, playing the love interest of Ellen's friend Audrey. Palillo also spent a year on the daytime show
One Life to Live and also acted in
Friday the 13th Part VI: Jason Lives (1986), and the lead in
The Curse of Micah Rood. He returned to New York City in 1991, and played such stage roles as Mozart in
Amadeus and regionally as George in ''
Who's Afraid of Virginia Woolf?, Arthur in Camelot, and Nathan Detroit in Guys and Dolls. He appeared on Broadway in 2008 in Broadway Backwards 4
, a charity event benefiting Broadway Cares/Equity Fights AIDS and the Lesbian, Gay, Bisexual and Transgender Community Center. Among his other New York City credits was a one-person show in 2000 where he portrayed Nazi criminal Adolf Eichmann in The Diary of Adolf Eichmann
off-Broadway. Palillo, in a newspaper interview in 1997, said he lamented his role as Horshack, as he was permanently typecast, which he believed had damaged his career. The following year, Palillo starred in The Fourposter'' at the
Wayside Theatre in Middletown, Virginia. As a director, Palillo led successful productions of the musical
Three Guys Naked from the Waist Down in Los Angeles,
A Closer Walk with Patsy Cline, and a new edition of
Phantom of the Opera at the Cuillo Center for the Arts in West Palm Beach, Florida. In 2007, he introduced a clothing line specializing in limited-edition T-shirts produced by Rotter and Friends. Palillo was also an artist, providing artwork for two children's books:
The Red Wings of Christmas and
A Gift for the Contessa. premiered at the Helen Hayes Theatre in
Nyack, New York, and later played at the
Queens Theatre in the Park in Queens, New York, and at El Dorado Springs High School in
El Dorado Springs, Missouri. ==Personal life and death==