Welcome Back, Kotter (1975-1979): Where are They Now?

Info derived from imdb. Only roles 2013 and later still being tracked. Only actors in 3+ (non-archive) episodes noted.

Gabe Kaplan (Gabe Kotter): last known acting role in 2007; as Self: Gotham Comedy Live (1 episode 2014).

Robert Hegyes (Juan Epstein): died in 2012.

Lawrence Hilton-Jacobs (Freddie 'Boom Boom' Washington): in Tamales and Gumbo (2015), Mercy for Angels (2015), Family Time (1 episode 2014), Airplane vs. Volcano (2014), Playin' for Love (2013), Let's Stay Together (1 episode 2013); 31 (2016) completed; Dead Man Rising (2015), Welcome to Where You've Always Been (2015) in post-production; as Self: Unsung Hollywood, The Sax Man (2014).

Marcia Strassman (Julie Kotter): died in 2014; in Looking for Mr. Right (2014).

John Sylvester White (Mr. Michael Woodman): died in 1988.

Ron Palillo (Arnold Horshack): died in 2012.

John Travolta (Vinnie Barbarino): in Life on the Line (2015), The Forger (2014), Kirstie (1 episode 2013), Killing Season (2013); Criminal Activities (2015), In a Valley of Violence (2016) completed; I Am Wrath (2016) in post-production; American Crime Story (10 episodes 2016) filming; Gotti (nd) in pre-production; as Self: The Insider (2 episodes 2014-2015), Extra (2 episodes 2015), Late Show with David Letterman (2 episodes 2013-2015), Entertainment Tonight (6 episodes 2013-2015), Good Morning America (3 episodes 2013-2015), E! Live from the Red Carpet (1 episode 2015), The Oscars (2015), Jimmy Kimmel Live! (1 episode 2015), East 'N' Style (1 episode 2014), Inside Edition (2 episodes 2014), The Oscars (2014), The Queen Latifah Show (1 episode 2013), The Tonight Show with Jay Leno (1 episode 2013), The Oscars (2013).

Stephen Shortridge (Beau De Labarre): last known acting role in 1989, as Self in 2000.

Helaine Lembeck (Judy Borden): last known acting role in 2009, as ADR Loop Group in 2011.

Vernee Watson (Vernajean Williams): in Fresh Off the Boat (1 episode 2015), Two and a Half Men (1 episode 2015), How Not to Propose (2015), The Exes (1 episode 2014), Selfie (1 episode 2014), Key and Peele (1 episode 2014), Jessie (1 episode 2014), Love That Girl! (1 episode 2014), Teen Wolf (1 episode 2014), Ironside (1 episode 2013), Beyond the Heavens (2013), Mr. Box Office (1 episode 2013), Suit Up (1 episode 2013), Highland Park (2013), Suburgatory (1 episode 2013), A.N.T. Farm (1 episode 2013); A Man Called Jon (2015) in post-production; as Director: Kimmie's Kitchen (unknown episodes 2013, 1 as Self).

Charles Fleischer (Carvelli): in Dystopia (2013); as Self: Lord of the Freaks (2015), Actors Entertainment (1 episode 2015).

Bob Harcum (Murray): last known acting role in 1981.

Melonie Haller (Angie Globagoski): no known subsequent acting roles.

Debralee Scott (Rosalie 'Hotsy' Totsy): died in 2005.

Irene Arranga (Mary Johnson): last known acting role in 1993, as Self in 2000.

Dennis Bowen (Todd Ludlow): died in 2012.

Ellen Travolta (Mrs. Horshack-O'Hara): last known acting role in 2009 but The Untold Story (2016) in post-production; Mistrust (2016) in pre-production.

Ernest Harada (Mr. Jan): last known acting role in 1996.

Sally Hightower (Laura Stevens): last known acting role in 1997.

Linda McCullough (Sally): last known acting role in 1994, then 1981 before that; as Editor in 2009.