Archie Bunker’s Place (he bought a bar, became a foster-grandfather to a precocious girl, etc.)
Carnac the Magnificent says: “What did the Robot say when Dr. Smith pulled a jar of Vasoline out of his pocket?”
Dare I say… band name?
Just in case some benighted soul here doesn’t realize it, this is where we get the phrase, "jumping the shark."
The consensus among most fans of HBO’s The Wire (at least those here on the SDMB) is that the first four seasons were consistently excellent (many of us think it was the best show on television ever), but the fifth was definitely a notch or two below the standards they had set. Characters behaved in uncharacteristic ways, concocted schemes that were highly improbable, and just generally betrayed the stark realism of seasons 1-4.
The Drew Carey Show was this (at times) funny and (at times) very different kind of show about this lovable loser who loved his best friend and was surrounded by zany characters in a dead end job in Ohio. Eventually it just all got screwed up. My understanding is that after season 4 as it slid in the ratings it was the only thing ABC had and so threw money at it to keep it going. They had the wacky in tiny doses Office Crab move in with Drew and killed the sexual tension by having Drew marry his friend. Bad ideas, but not as bad as continuing for 3 more years as Drew has multiple marriages, marries his male boss, gets a job at an Internet Company loses a main character to Scrubs etc.
I think “the moment” tho if I had to was the Drew-Kate/Christa marriage
BTW Christa Miller, Craig Ferguson, Cary, and the rest never won or were nominated for a single Emmy for this show.
Wow! Two whole replies to one of my posts. I’m not invisible, after all! 
Anyway, I’m used to the idea that my idea of funny can be rather idiosyncratic. Besides, I’m not saying that *Ellen *went from mediocre to comedy gold. More like it went from mediocre to a higher level (IMO) of mediocre. (Except for the coming out episode itself–I agree that it was comedy gold.)
I can’t believe I’m the first person to mention Melrose Place. The show started off as a spinoff of 90210. Melrose Place was supposed to show real life in your early 20s. An introduction to the real world.
That didn’t work so it got turned into the popular soap opera.
I’d also say Beverly Hills, 90210 qualifies. The high school episodes are very different than the college years. The high school years were a typical teenage show. The college years got further and further away from reality.
I second the Simpsons. For me, there is a clear and well-defined moment - the death of Maude Flanders.
Up until this point, the series had been grounded in the Simpsons family and the surrounding characters of Springfield. Wacky stuff would happen, but there was a sense that the writers cared about the relationships between the citizens of Springfield.
When Maude Flanders was killed unexpectedly (and in a fairly distasteful manner) I began to see that the tone had shifted. Character relationships? Abandoned to get a few quick lulz with crazy gags. And lots and lots of jerk-ass Homer, instead of a bumbling Homer that was a fool but loved his family.
Granted, there is a back story as to why Maude had to die - the voice actor for Maude had been denied a pay increase and simply walked. But this for me was the bright line - the series had been moving more towards cheap one-off gags at the expense of the cohesive Springfield universe.
Maude’s death was the exact Sunday when I stopped making any effort to watch new episodes of The Simpsons.
But at least the writers were inclined to take the alternate-history angle seriously early on. The hippie episode, for instance, hinged on a Japanese victory at the Battle of the Coral Sea. The world threatened by an asteroid had no atomic weapons because Albert Einstein insisted they were impossible. After a while, the writers just started saying, “Uh … this world’s, you know, DIFFERENT.”
The first few episodes of Seinfeld were focused on Jerry. The show became funnier as Jerry became the backseat driver in his friends’ lives.
Similarly, the Andy Griffith Show became better as it focused less on Andy and more on some of the oddball characters in Mayberry, particularly Barney Fife.
I remember this, to me it seemed like the show went from “The Drew Carey Show” to “The Crazy Mimi Show with Drew Carey”. It just wasn’t as interesting after that.
Off topic: it is interesting to see Drew on The Price is Right now. I’m not sure if he is really enjoying himself or not.
The Simpsons did take a huge gamble with the first “Halloween Show.” I am so thankful that “Treehouse of Horror” became a tradition.
Lately I’ve been watching Buck Rogers in the 25th Century reruns and in addition to noting what an eminently fuckable babe Erin Gray was (and still is, to a degree), I’m reminded of just how screwed up that third season was, with The Searcher and Hawk and the arrogant robot and such.
Gray’s third-season costume, though, a short-skirt proto-Sailor Moon number, is the only bright spot.