What's a show that got cancelled way too early that genuinely still haunts you years later

[DarkEnergy27]

Every few years there seems to be a show that builds real momentum, develops a genuinely loyal following, and then just gets quietly cancelled before the story ever gets a proper conclusion, leaving fans stuck permanently wondering what could have been. Curious what show still genuinely bothers people the most, years after the fact.

Mine is a fairly niche sci-fi series that got cut after two seasons right as it was clearly building toward something much bigger. And I still think about the dangling plot threads more than shows that actually got a proper full run and ending.

There is something uniquely frustrating about early cancellation compared to a show simply running its course and ending naturally. Since there is no closure at all, just an abrupt stop mid conversation that never really resolves.

Would love to hear what other people are still quietly mourning. Whether it is something genuinely obscure that barely anyone else remembers, or something bigger that got a surprisingly large fan campaign to try to save it at the time.
Bonus points if you can articulate exactly what direction you think the story was actually building toward before it got abruptly cut short, always curious how differently people imagine the same unfinished ending