TV shows
King of the Hill, had a good really good run and lasted a long while, just wish it ended on the creators terms not to make way for a Family Guy spin off.
Beavis and Butthead reboot, that was so good, I have no idea why it only lasted one season.
Ash vs the Dead, felt it had another season or two in it.
Moral Orel, while the last season is the best and does give Orel himself a good ending, I fell the show should have ended with the original planned 5 seasons before it was cancled for being too dark for Adult Swim.
Movies:
Guillermo del Toro's At the Mountains of Madness, feel like he was the right person to do a big budget version of this, studios always seemed to get cold feet however.
Flash Gordon reboot by Fox, Disney just canceled that when they bought Fox, they had Thor: Ragnarok director Taika Waititi on board, would have really liked to see what he would do with a big budget movie without the Marvel baggage
Ben Affleck's Rigged McDonald’s Monopoly Sweepstakes movie, sounded great and he seems like a great pick going off the Town and Gone Baby Gone, could have been the budget being much, so no idea why Disney canceled it. Here is a news story about the whole deal
https://www.businessinsider.com/mcdonalds-monopoly-game-rigged-scam-report-2018-7?r=US&IR=T
Ronnie Rocket, a movie that David Lynch has tried a few times to get made over the years, " Ronnie Rocket concerned the story of a detective seeking to enter a mysterious second dimension, aided by his ability to stand on one leg. He is being obstructed on this quest by a strange landscape of odd rooms and a threatening train; while being stalked by the "Donut Men", who wield electricity as a weapon. In addition to the detective's story, the film was to show the tale of Ronald d'Arte, a teenage dwarf, who suffers a surgical mishap which leaves him dependent on being plugged into an electrical supply at regular intervals; this dependence grants him an affinity over electricity which he can use to produce music or cause destruction. The boy names himself Ronnie Rocket and becomes a rock star, befriending a tap-dancer named Electra-Cute"