The 1977 sitcom, Three's Company, was a runaway hit. It ultimately spanned eight seasons with 172 episodes, and multiple spinoffs and gained another lifetime in syndication.
Joyce DeWitt became immensely famous from starring in "Three's Company," and is the only actor other than John Ritter to appear in almost every episode of the series.
DeWitt became a household name playing Janet Wood, but after the show, she semi-retired from acting. From 1984 to 1991, she lived far out of the public eye.
DeWitt resurfaced for a stage production of "Noises Off!" Since 1995, she has made occasional appearances playing herself on TV shows. Now 74, she will likely continue to work.
On "Three's Company," Richard Kline played Larry, Jack's close friend, and charming yet slimy used car salesman who lied about his identity to pick up women.
"Three's Company" was part of a vast acting career for Kline. He played dozens of supporting roles, and was the lead in "Noah Knows Best" and "Inside Schwartz."
In the fifth season, Chrissy was replaced by her cousin Cindy, played by Jenilee Harrison. She was on for two seasons, then replaced by Priscilla Barnes.
After the show, Harrison was in 69 episodes of "Dallas" and several films. She seems to have retired from acting in 2002, with her last credit being the TV movie "The Power."
Priscilla Barnes played Terri Alden in the final two seasons and was clearly meant to serve as a Chrissy/Cindy stand-in, though in less of a “shallow blonde” way.
Barnes has an extensive filmography including nearly every genre from the 1990s. More recently, she had a recurring role on "Jane the Virgin," appearing in 41 episodes.