Other media are fine too. Let’s talk about works that ended (often prematurely) only to be wrapped up in some other work, or characters that got a second chance elsewhere. Some examples:
My name is Earl - I forget which show, but wasn’t there some new report in another show about Earl finally completing his list?
Scrubs / Cougar Town - on the latest episode we see the singing guy from Scrubs in Hawaii, lamenting his breakup with the Gooch.
Millenium / TLG / X-Files - Both Millenium and TLG ended before getting resolutions, and got resolutions of a sort in episodes of the X-Files.
Cheers / Frasier - a bunch of Cheers alumni got send off episodes on Frasier.
Firefly got a wrap up movie in Serenity.
We can also chat about works that jumped back and forth between media (canon only):
X-Files got one mid-series motion picture, and one post.
The Dark Tower project is supposed to consist of a few seasons of TV intermixed with a few motion pictures.
In the premiere of Raising Hope, the TV announcer said something like “A local man has just completed a list of good deeds – and you won’t believe how the did it.”
The dramatic show, I’ll Fly Away was resolved in a one-time special on PBS; the original was broadcast on NBC. Most of the original cast returned; the main missing person was Jeremy Loudon, but his role was taken by his twin brother, Jason (who missed out on the role originally because he was unavailable.
Everyone remembers that Newhart ended with it all being a dream of the characters of The Bob Newhart Show. Few remember that there was a Bob Newhart Show reunion that continues from that point, with Bob going into work talking about that weird dream he just had about owning an inn. The end of that had him running into Larry, Darryl, and Darryl in the elevator.
The cliffhanger of the cancelled Alien Nation was resolved in a series of TV movies.
The movie Dogma opens in Illinois. The characters of Jay and Silent Bob appear in the movie. There’s no explanation in the movie about why the two characters, who have always been seen in New Jersey, are in Illinois.
But Kevin Smith wrote a comic book series about the two characters which was set between the events of Chasing Amy and Dogma and showed Jay and Silent Bob wandering around the country. The last page of the comic book was the scene of their first appearance in Dogma.
I am pretty sure the show Jericho was concluded in a comic book.
It isn’t quite the same thing but several years ago, there was a series of paper back Star Trek novels that each ended on a cliff hanger (one novel for each series they published at the time). To get the resolutions of all the cliff hangers, you had to buy a hard cover book. I don’t think anyone was happy about that one.
Donald Westlake did a series of caper novels featuring John Dortmunder, an only moderately successful burglar, and his regular crew. Westlake did a number of stand-alone books, as well, and in one of them (Dancing Aztecs, I think) a character has a problem with his car and the whole Dortmunder cast shows up to help him out, and are never seen again in the book.
The comic strip John Darling was a spin-off from Funky Winkerbean. The strip ended abruptly when the title character was shot to death for no apparent reason.
Six years later, the murder was solved in a *Funky Winkerbean *story line.
Not a conclusion, but an extension: there was aBabylon 5 comic book during the run of the show that was part of the official continuity. If you read it you could discover a broad hint at an important revalation that wasn’t aired until long after the comic came out.
Batman: Beyond as a whole got its conclusion in JLI. One of the last episodes of the show is a flash-forward to Terry confronting an elderly Amanda Waller over her possible involvement in his parents death.
Soap (TV series from late 70s). Jessica Tate was in front of a firing squad in the last show; I don’t think the writers knew at that point that it was being canceled.
She appeared in an episode of Benson, something about having to do a good deed before she was either revived, or went to heaven (wasn’t clear on which). Benson was a spinoff of the butler’s character on Soap.
Robotech. It’s pretty complicated… it’s a 1985 show that adapted three separate Japanese cartoons, and while the show was originally sold as a single 85-episode series, it was semi-formally accepted to be a three-part series that spans three generations, with long gaps of time between them:
Robotech: The Macross Saga
Robotech: The Masters
Robotech: The New Generation
In the original continuity, a prequel to Macross was released in graphic novel format, a sequel to Macross was released as a straight-to-video film (Robotech II: The Sentinels, which was made of the first three episodes of a proposed/canceled series). This sequel, in turn, was finished off in novels and comics. A theatrically released movie that acted as a bridge from Macross to Masters saw limited release in 1986. Several series of comics and novels covered events that happened concurrently with Macross, and a coda to the entire series was released in comic and novel form. To follow the entire story, then, you have to jump between from a graphic novel to the TV series, multiple series of comics, two series of novels, a theatrical film, and an OVA film.
The new accepted continuity pares it down quite a bit, and less is “canon.” Now it’s just the original three TV series, followed by the 2006 theatrical release Robotech: The Shadow Chronicles.
Before those came out, it was resolved in a comic book.
The Ralph Bakshi Lord of the Rings cartoon ended without finishing the story (and existed in at least two different versions, by the way. I’ve seen two differently cut versions in theaters). The 1980 Rankin-Bass TV -movie cartoon The Return of the King essentially finished the story. It supposedly wasn’t intended that way, but it doesn’t make any sense to make The Return of the King without fuilming everything that went before it.