I'm an 80's baby. The term is used a bit too loosely these days with the retro resurgence going on, but I lived through the Reagan era as a child. So if you're unfamilar with Oliver North, The Care Bears, Punky Brewster, and/or Garbage Pail Kids, you don't count!! Along with the crack epidemic, everyday I witnessed the fried egg commercial which illustrated what my brain on drugs would look like. Besides the huge strides that Hip-Hop made towards the latter half of the decade, the 80's also brought us the now deceased half hour sitcom. Oh, how I loved these sitcoms!!!
There are too many to mention, and despite how cheesy some of them may have been, the writing was dope. I think the proof is in the "invisible characters" we never saw but came to know. For me, the first and one of the most memorable was "The Gooch" from Different Strokes. He was the bully that tortured Arnold during his academic career. It wasn't until later seasons that "The Gooch" would be casted and become a reoccurring character who was played by Forrest Whitaker!! Before that point though, "The Gooch" was simply the bully whose whoop asses and teasing we heard about.
By far, my favorite show of that era, and even into the early 90's, was The Cosby Show. Yeah the casting may have been a bit off when Sondra's date in an earlier episode would later become Denise's future husband and Olivia's dad (around the 8:30), but TV has no memory right? I think the 2 most famous invisible characters have to be fashion designer, Gordon Gartrell, and the lesser known, Eunice Chantilly. I'll assume you all know Gordon, so I'll focus on Eunice.
For the uninitiated, Eunice was Cliff's "other" high school sweetheart. In tons of episodes, Claire references "Eunice" and we easily see her distaste for her longtime arch nemesis. Similar to "The Gooch", she played a huge part in the show's mythology, and that's a testament to the great writing. We know them, their histories, their personality traits, yet we never saw them. Long live the 30 minute sitcom and all of it's "invisible characters".