Thomas Wolfe famously wrote that you can't go home again. However, that has oft been debunked, most evident in the high school sitcom, Welcome Back, Kotter, which anchored ABC's Thursday lineup during its first three seasons before being shunted off to Mondays---and inevitable cancellation---in season 4 to make room for Mork & Mindy.
Speaking of anchors, co-creator Gabriel Kaplan anchored the show's ensemble cast as school teacher Gabriel Kotter, who returned to his alma mater of James Buchanan High in Brooklyn, and, in a case of irony, taking over the very same remedial education class he himself was a part of as a student. In other words, he was a founding member of the Sweathogs, and thus acted as a friend and mentor to the current group, which led to them visiting him at home at the most inopportune times.
The Sweathogs were a diverse bunch, with Vinnie Barbarino (John Travolta) as their de facto leader. Then, there was athletic, suave Freddie "Boom Boom" Washington (Lawrence Hilton-Jacobs), geeky but dull witted Arnold Horshack (Ron Palillo), and slippery Juan Epstein (Robert Hegyes), who was forever fabricating excuses from his mother to get out of class or tough homework assignments, to the point where it became cliched and predictable. One thing that Epstein had in his favor was the fact that he & Kotter shared a fondness for the Marx Brothers, as evidenced by Epstein answering Kotter's Groucho Marx mimic by imitating Chico (or, sometimes, Harpo).
Welcome Back, Kotter also opened doors for some of the supporting cast. For example, Charles Fleischer (Carvelli), who was never considered a series regular due to the infrequency of his appearances, had time to co-host the short lived children's variety show, Wacko, during season 3. Debralee Scott (Rosalie Totsie) left after 1 season to co-star on Mary Hartman, Mary Hartman before returning for a 1-shot later in the series. Vernee Watson appeared frequently during the first couple of seasons, then left for a beefier role on Carter Country.
It was clear, however, that John Travolta has had the most success thanks to Kotter. He began a recording career during season 1, and had starred in some major blockbusters after each of the first three seasons ("Carrie", "Saturday Night Fever", & "Grease"), such that he was reduced to "special guest" status in season 4, appearing in 8 episodes. That prompted the producers to introduce a new Sweathog, Beau De la Barre (Stephen Shortridge) in season 4, but he wasn't quite the answer. After Kotter ended, Shortridge & Fleischer co-starred with Debbie Reynolds in a short-lived Aaron Spelling offering for ABC, Aloha Paradise. Shortridge wasn't heard from much again after that.
Perhaps ABC fumbled by moving Kotter to Mondays, but, then, they didn't want to risk breaking up their successful Tuesday block, anchored by Happy Days & Laverne & Shirley, which, despite being set in a different time period, could actually have complemented Kotter because both shows appealed to the same audience as Kotter. The Sweathogs were popular enough such that Welcome Back, Kotter transitioned into comics, with a 10 issue run at DC between 1976-77, but as yet not yet collected in trade paperback.
Sonic540 uploaded the familiar open that everyone knows, with the theme composed and sung by former Lovin' Spoonful frontman John Sebastian.......