For eight of its nine seasons, Roseanne had Halloween episodes. I'm not sure how many of them I saw when they first aired, nor did I remember any plots. But one thing I always remembered was that there were some really neat Jack-o-Lanterns in those episodes. Anyway, in 2016 I got a DVD with all eight episodes, which I wanted to watch throughout October of that year, so I could write reviews of each episode. (I had actually been meaning to do this for a few years, before I finally got around to buying the DVD.) I suppose I should mention that there may be some context of whatever's going on each season in the regular episodes that might have affected these episodes, of which I wouldn't be aware.

BOO! (Season 2; Oct. 31, 1989)
Halloween Specials Wiki; IMDb; Wikia

It's fairly simple as far as plot is concerned. But it's pretty cool, because the Conner family goes all out for Halloween, in terms of costumes, decorations, and so forth. Dan and Roseanne each try to scare the other several times. There's not much else to say about the episode, but it's definitely funny, start to finish.

Trick or Treat (Season 3; Oct. 30, 1990)
Halloween Specials Wiki; IMDb; Wikia

This year there weren't as many decorations at the Conner house, because they were all going to Dan's lodge for Halloween. However, we don't get to see very much of the lodge (though what little we did see was pretty cool, I thought... even if Darlene thought it was lame). Their costumes were pretty good, though. (Dan went as the Three Stooges.) But there was more of a plot this time: Dan was upset about DJ dressing as a witch, and tried to convince him to go as a warlock, instead, but DJ was adamant. I think Dan was mostly worried about other kids potentially beating DJ up for wearing a "girl's costume," though there may have been some more direct transphobia involved. (It's amazing- and sad- how timely this plot remains, twenty-six years later.) But Dan eventually comes around. Meanwhile, Roseanne and Jackie's car breaks down on the way to the lodge, and they have to call Dan from a bar. Earlier, back at Roseanne's house, we'd seen a bit of Jackie's cat costume, but she had taken it off before going into the bar. However, Roseanne was dressed as a man, which served as a nice counterpoint to the DJ plot. And she had some fun interacting with the guys at the bar, who had no idea she was a woman. Anyway, the whole episode was amusing, and just a bit groundbreaking in challenging gender norms.

Trick Me Up, Trick Me Down (Season 4; Oct. 29, 1991)
Halloween Specials Wiki; IMDb; Wikia

It starts with a neighbor named Kathy showing up at the Conners' house. Roseanne and Dan prank her into thinking Roseanne has murdered Dan. Later, Roseanne and Dan go to Dan's lodge for a Halloween party (they're dressed as a ventriloquist and dummy who have both died). Jackie is also there, dressed as Morticia Addams. And Arnie is there, dressed as the ghost of Elvis (the same costume he wore in last year's Halloween episode). Kathy and her husband Jerry also show up, and Roseanne is certain Kathy has only come to pull some kind of prank on her as payback for the prank she and Dan pulled on Kathy. Meanwhile, Jackie spends some time talking with a guy in a moose costume, who eventually turns out to be her ex-boyfriend Booker. (I don't remember this character at all from when I originally watched the series, but he's played by George Clooney.) And... I dunno what else to say about the plot, except that as always, it was funny.
Also, it seems this was the first year that there were Jack-o-Lanterns as the backdrop for the closing credits.

Halloween IV (Season 5; Oct. 27, 1992)
Halloween Specials Wiki; IMDb; Wikia

Roseanne has lost her Halloween spirit because Becky wouldn't be home for the holiday (and I guess other stuff had happened that year to upset Roseanne, but I dunno what). Anyway, she decides to stay home alone while everyone else goes to the annual lodge party, and she falls asleep on the couch. Then she has a Christmas Carol type of dream that restores her Halloween spirit, and she ends up going to the party, after all. It was a pretty decent episode.

Halloween V (Season 6; Oct. 26, 1993)
Halloween Specials Wiki; IMDb; Wikia

Roseanne wants Nancy to be part of a group costume (the Cleavers), but Nancy doesn't want to, because she thinks Dan doesn't like her. And she's right. Meanwhile, Darlene is away at school, and calls Roseanne to say she won't be able to come home, because she's going to a party with some guy. Roseanne isn't happy to hear that she might be cheating on David, who is still living with the Conners. But then he has a new friend named Sally, and Roseanne is worried that he might be cheating on Darlene. Anyway, we don't see any of the lodge this year (though it is mentioned). The scenes are all set either at the Conner house or at the Lunch Box. As usual, there are pranks. And it's all really funny. Also, it surprises me that apparently there were only two Halloween episodes with Jack-o-Lanterns in the closing credits. I could have sworn it happened every year, but I guess I was wrong. Just '91 and '93. Oh well.

Skeleton in the Closet (Season 7; Oct. 26, 1994)
Halloween Specials Wiki; IMDb; Wikia

Rather than going to the usual Halloween party at the lodge, this year Dan and Roseanne go to a party Leon is throwing at the Lunch Box. (Leon is dressed as Hillary Clinton, so I think it pretty apt that I watched this in 2016.) And as always, various pranks are involved, including one Bev plays on Roseanne. And... to say anything else about the episode would probably be too spoilery.

Halloween: The Final Chapter (Season 8; Oct. 31, 1995)
Halloween Specials Wiki; IMDb; Wikia

The episode starts with a seance. Then there's a ridiculously fun duel between witch Jackie and gypsy Roseanne. Then a ouija session that goes nowhere. Then an in-joke I won't spoil, involving a woman stopping by with her kids trick-or-treating. And some more amusing trick-or-treaters. And then a sort of Mummenschanz-style blacklight performance. (It's funny, because I had been thinking about Mummenschanz earlier in the day that I watched this in 2016, for unrelated reasons. So the coincidence of having the blacklight thing happen in this episode would be really surprising, if I weren't such a coincidence magnet.) Later in the episode there's more ouija stuff, which leads into a major event that I won't spoil, except to say that it involves Roseanne having some weird dreams/hallucinations (including flashbacks to previous Halloween episodes). Anyway, it was all pretty cool.

Satan, Darling (Season 9; Oct. 29, 1996)
IMDb; Wikia

This isn't technically a Halloween episode, though it pretty obviously had a Halloween vibe. And I must say that I never saw any of the final season, but it was very different from every other season of the show, for a reason I don't want to spoil. But I will say that Roseanne and Jackie and Nancy are at a fancy party in New York, full of wealthy socialites. And there are several fun guest stars, most notably Patsy and Eddy from Absolutely Fabulous. And then partway through the episode, Roseanne has a weird dream in which she takes a drink offered by a group of witches, after which she's talking to a very pregnant Darlene, and the whole thing turns into a spoof of Rosemary's Baby. So, yeah, it was a really fun and funny episode. (Though I'd definitely say the best parts were Eddy's interactions with Roseanne and Patsy's interactions with Jackie.)