Was there a seriously intense-water-cooler-these are-my theories-show before

Lost and the Battlestar Galactica reboot?

There was the ‘Oh shit how will they get out of this’ of TNGs Best of Both Worlds…but thats just one ep. I don’t think The Prisoner had a strong enough following or enough established lore to spawn that sort of thing.

The first season of True Detective certainly had that.

I think the “Who shot J.R.?” storyline of Dallas was the original, pre-Internet entertainment mystery phenomenon. People wouldn’t shut the fuck up about it all through 1980, and it seemed like every news program tried to capture the cultural zeitgeist of it by attempting to put their own spin on it. Even 60 Minutes, which considers itself to be the premier hard newsmagazine program that is above such antics, got in on the ‘fun’, and of course it was so widely parodied that even people who never watched the show remember the context.

I’m sure there is precedent before that–the death of Sherlock Holmes sparked much discussion and controversy, and of course “The Game” is a long standing tradition among Arthur Conan Doyle fans–but I think for television that was really the first singular ‘water cooler discussion’ event. The Fugitive was very popular in its day with a long-running mystery about the one-armed man but I don’t think it spurred that kind of regular discussion or theorizing.

Stranger

Good one…i was at a HS football game when the revealing ep aired and the announcer revealed who had done it over the loudspeaker.

I just recalled a JR-like moment that preceded Dallas, though not nearly as intense…

“Jessica Tate did not kill Peter Campbell…one of these five did.”

Did Twin Peaks have enough of a mainstream audience to rate as water-cooler fodder? Its original airing was a little before my time (I was alive, but all of four years old), although it retained a strong cult following that carried over into my own generation. But I watched it, on DVD, in the internet age, when every conceivable detail about it could be easily Googled. It must have been a fucked-up experience to try to make sense of the show in 1990.

The X-Files? 24?

It definitely did, at least for its first season. I remember my co-workers being fascinated by it, and lots of speculation as to what was actually going on.

Possibly, The Fugitive 1963 series. Was there really a One Armed man?

“It was not until episode 14, “The Girl from Little Egypt”, that viewers were offered the full details of Richard Kimble’s plight. A series of flashbacks reveals the fateful night of Helen Kimble’s death, and for the first time offers a glimpse of the “One-Armed Man”.”

Source: https://en.wikipedia.org/wiki/The_Fugitive_(1963_TV_series)

Not a continuing series, but I’m sure the open-ended episodes of The Alfred Hitchcock Hour and The Twilight Zone lead to next day discussions.

Keep in mind that prior to the 70’s and 80’s, the majority of people were probably watching one of the three major network’s shows and that would be the topic of discussion, “seriously intense” or not the next day.

Heroes

Strictly speaking, the first seasons of Survivor: the ratings were crazy high, and viewers prone to speculation kept excitedly discussing the secret alliance between the pudgy gay nudist and the seventysomething Navy SEAL — or a fake merge, or a possible betrayal — or an intentional loss during a competition, or an offer to give away individual immunity after one — or stealing the other tribe’s shoes, or lying about a dead grandmother — anything, everything.

Yeah, I remember lots of chatter right here on the SDMB about Heroes.

Almost every soap opera ever.

Oh! Buffy the Vampire Slayer and Angel!

Babylon 5? I remember discussions online about it.

Brian

I was around for both of these. The media frenzy in both cases was crazy. I’m going to say in the case of Twin Peaks, it was just a little crazier, mainly because everyone assumed the big reveal would come at the end of the first season, and it didn’t, but also because there were lots of clues dropped in the episodes, so it seemed that people ought to be able to figure it out.

There was tons of discussion because there was tons of theorizing, and “proof-texting” for lack of a better term, to back up one’s theorizing.

But also, “Who shot JR?” happened in 1980. A few people had VCRs, but there weren’t many out there, and since no one knew what was in the offing, people had not taped the whole season in anticipation of a mystery at the end.

On the other hand, Twin Peaks was 10 years later, and directed by someone famous-- really, really famous, just having come off of Blue Velvet. We kind of had an idea that this would be a protracted mystery, and at any rate, it was directed by David Lynch. Moreover, pretty much everyone had a VCR by 1990. So there were lots and lots of tapes of the whole season circulating after the fact.

Basically, way more people watched Twin Peaks than Dallas. Even with summer reruns. And getting together and watching Twin Peaks as a group was a thing. I don’t think Dallas groups was a thing, albeit, I was in jr. high/a high school freshman for Dallas, and just out of college for Twin Peaks. But I also know my parents and brother watched Twin Peaks, and never Dallas.

It’s also true that a book called The Diary of Laura Palmer, authorized by the TV production company, and written by David Lynch’s daughter, became a best-seller over the summer between the first and second season of Twin Peaks, and there was a whole cottage industry of T-shirts and bumper stickers. There were some T-shirts and even a novelty song about “Who shot JR?” but all-in-all, it didn’t generate what Twin Peaks did.

However, without the JR phenomenon, I don’t know if people would have been “ready” for Twin Peaks. End of the season cliff-hangers weren’t really considered “fair” before Dallas, but now they happen with nearly every shot, all the time. If it hadn’t been for Dallas coming before, I think people would have been much, much angrier about the cliff-hanger at the end of the first season of Twin Peaks, and there could have been a sort of backlash that stopped people watching altogether.

I think you’re remembering incorrectly. While Twin Peaks was a critical darling and had a rabid fan base, it was a little bit too weird for most people and the media landscape had begun fracturing (nothing compared to now - but there was cable.)

The Dallas episode where they revealed “Who Shot JR” had a 76 share - 83 million people watched it. (cite) In contrast - Twin Peaks never made it above about 35 million viewers. (cite) (Also while most people did have VCRs, those same people were horrible at programming them. For most people, VCRs were ok at taping things you were watching for rewatching later. Watching one channel and taping another or taping something to watch later was outside of a lot of VCR owners’ skills set.)

The problem with the cite is that it just tells you how many TVs were tuned in, not how many people were actually watching, and Twin Peaks gatherings were a real thing. You’d have anywhere from 6-15 people watching half the TVs tuned into it.

The “Who shot JR reveal” may have been highly watched, but I think it translated into less general interest in the whole series than the interest in Twin Peaks in general was. My family watched that particular episode, but it’s remains the only episode I’ve ever seen, and I slept through most of it. My aunt woke me up to see the “reveal.” I didn’t remember it the next morning.

Who Shot JR was probably bigger but I definitely remember hearing Twin Peaks stuff on the regular and, despite not watching it myself, still absorbed enough of the conversation to have some idea of what was being said at the water cooler. I think the main difference is that Who Shot JR was just around that one point rather than Dallas in general being water cooler talk but Twin Peaks was water cooler talk from the start.

Dallas was the number 1 show in the country in 1980, 1981, and 83. It was top 5 for all of the early 80s. Twin Peaks didn’t crack the top 40 during its run.

Even with watching parties, very many more people watched Dallas than Twin Peaks.

ETA: I was so young during Dallas that I wasn’t allowed to watch it - and I knew who shot JR & “it was all a dream.”
On the other side - I was the only person I knew who watched Twin Peaks.