What are some examples of some of the most well-known and watched TV series at the time that been forgotten culturally?

The Drew Carey Show. It was huge in the 90s, yet there aren't a lot of memes or quotes from the show that get passed around on the Internet. It didn't help that they only put out the first season on DVD and that it wasn't streaming for a lot of years.

Lost
It was a HUGE deal when it was airing, only to be undone when everyone realized the show's title was not describing the characters. It was describing the show's writers.
- Lost was one of the first of the show got too big too famous too much of a cash cow it was forced to drag on instead of just end in a way that makes sense. Eventually they just literally run out of ideas that make any sense.
  We see that now with streaming. Show does a banger season 1, probably could end with a banger season 2. Series milked for 4 or 5 seasons to the point the original fans no longer even watch it.
  
  Kind of, they also refused to pay the cast so they kept killing off characters that should have been around for different plot lines. Was hard for the writers to keep up with execs fucking them over and still have a cohesive story.
  Probably not an uncommon experience it film and tv

MAS*H
Mary Tyler Moore Show
Leave it to Beaver
Mattlock
Murder she wrote
Perry Mason
X Files
Buffy the Vampire Slayer
COPS
Jerry Springer
Cosby Show (no surprise there)
Tonight show with Johnny Carson (also with Jay Leno i suppose but fuck that guy anyways)
Ed Harrison Show
Xena: Warrior Princess
I Love Lucy
MacGuyver
E.R.
Flintstones
Jetsons
Bradey Bunch
Gilligan's Island
Quantum Leap
Sliders (i loved this show, not sure how popular it actually was)
Red Green Show
Barney
Teletubbies
Remington Steele
Twilight Zone
Outer Limits
Perry Mason (damn gonna listen to the ozzy song now that im reminded of it)
Mythbusters
Orange County Choppers
Ducktales
I dont see anyone directly referencing these shows in any significant way, nor do i hear anyone talking about them unless something specifically references them. Ill accept some of them may not meet the standard asking here, fair enough, but think its gonna be a lot of disagreement in general anyway.
Oh thought of more
Magnum P.I.
Bonanza
Anne of Green Gables (though i did just come across an anime version of this)
Touched by an Angel
Little house on the Prairie
Corner Gas
Highlander
Three's Company
GI Joe
- Since you came up with some oldie's I would add Happy days To your list
  
  Happy days! Thanks forgot about that one

Two and a Half Men was big for a long time and gets pretty much ignored nowadays - which is probably fair tbh, it lost its soul pretty fast
- Also the whole Charlie Sheen issues....

I'm amazed at how The Golden Girls gets so much love, but nobody talks about Designing Women. That was a great show, excellent writing, killer cast, still relatable... it deserves more attention.

Maude. Everyone remembers Bea Arthur for The Golden Girls, but forgets about the hit show she starred in before that. Like GG, Maude was bold, especially for a show about a middle class marriage. At one point, Maude even had an abortion.

How I Met Your Mother. I swear to god that show was huge in the late aughts and really reignited NPH’s career. Flash forward to today and the only time anybody ever even mentions it, is about how a bad ending can ruin a whole series and even there it comes in second to Game of Thrones.
- I loved HIMYM when it was airing. I feel like people gloss over just how bad the entire last season was. After watching that show from day one I quit halfway through the last season, with the intention of just binging it once it was done. Then I heard about the ending. It was such a guy punch that I will never rewatch it, not even the early seasons. I'm sure that is why it doesn't have the staying power of shows like the Office and Parks and Rec that you can watch over and over.
- My friend and his wife got into the reruns this year after having never watched it. I warned them to just stop 3 or 4 seasons in that they've enjoyed it at its peak and there's nothing more to see there. They didn't listen. Now they regret it and went from loving it to hating it

Game of Thrones ended so badly that nobody talks about it anymore. You'll hear the occasional quotes that were memorable, but nobody really cares about the show anymore.
- Freefolk remembers. God how unbelievably shit it was, it's unfathomably bad
  
  If thats how his books were gonna end, no wonder he stopped writing.
- Lost would be similar to that. It was huge when it was on, then it ended badly and everyone ignores it now, except for talking about how badly it ended
  
  The only thing worse than the ending is the insufferable people who will endlessly try to convince you how perfect the ending was simply because it's subverted expectations. Well yeah, everybody turning into a fucking Autobots and blasting off into space would subvert expectations too. That alone doesn't make it a good ending.
  
  God Lost was inescapable and then suddenly it was fucking goooone. I never watched it but it was fascinating to see just how poof gone it was.

I was just saying to a coworker the other day that I'm kind of surprised no one has gone back to do anything Dawson's Creek related. I swear that show was everyfuckingwhere when it first aired.

Knight Rider
- I binged the whole series and the series finale was just a normal episode, and a bad one. I was like, that's fuckin it? So damn bizarre.

Laugh In.
Deservedly so.

SOAP. It was hilarious, ground-breaking, and a generational touchstone. It was pushing boundaries and challenging conventions, all while ostensibly a parody of soap operas.
- It's amazing how times have changed since SOAP first aired. At the time, it was groundbreaking, a real breath of fresh air, and completely hilarious. Nowadays, it's CRINGE! It helped to change the culture, but also rendered itself obsolete.
- It brought the first gay man into living rooms across the country.

Alf Family ties
Both were pretty huge at the time but they are not revived or memed. The golden girls is still remembered, but so much unused meme material.
- I tried watching ALF not too long ago. It didn't really hold up. It was just okay. The humor felt flat and one note. I grew up watching it and even the nostalgia vibe didn't keep me interested. Golden Girls on the other hand will still have me cracking up every episode.
  
  Yes and still occasionally brought up. Sex and the city was a phenomenon. It's not mentioned much any more. The sopranos and 24, we're similarly huge but now ignored, whereas shows like lost and game of thrones that faded at their ends are still part of the discourse.

Dallas
the ending ruined its legacy
- Thank you!
  Was trying to remember that one and kept thinking Dynasty and while that was a show it wasn't the one i was think of.

Dynasty.
So many people think it took place in Texas…it was Denver, Colorado and surrounding areas (although a lot was filmed in California).
It was a nighttime soap opera that tackled a lot of socially tricky topics (being gay, oil & gas industry, women’s rights, Joan Collins’s wardrobe). Until it got weird and aliens and shit showed up.
- Dallas was the one that took place in Texas, since it started a few years earlier that's probably why people think of it first when confronted with the idea of late night soaps. Especially with the sharks they jumped in later seasons.
  
  It cracks me up because obviously “Dallas” is right there in the name for that one. Yes, absolutely Dynasty was ABC’s answer to Dallas (on CBS) and they are SO similar. I’ve had a handful of people who are totally convinced Dynasty took place in Texas and get angry and refuse to believe it when the internet says otherwise (or I point out Denver’s downtown is in the opening credits). Mandela effect I guess…
- Googled and there weren't aliens in Dynasty. That was The Colby's.
  
  That was originally called Dynasty II: The Colbys, but they probably dropped the first part to make it easier or something. It follows the same characters though. Basically a failed reboot.

NYPD Blue showed the first naked butt on TV.
- Jimmy Smitts?

The Walking Dead

sopranos