In Aladdin: The Return of Jafar, the titular villain is killed when his lamp is kicked into lava by Iago, an act that cements that Iago really is sincere about hisHeel–Face Turn. Jafar explodes in a ball of light, and disappears forever. The cartoon series that followed, which Return of Jafar was meant to introduce, kept Jafar permanently gone outside of a few mentions of his name, ensuring he truly was dead. The Grand FinaleThe King of Thieves also insists that the events will happen "without Jafar and all of his malice," and sticks to it.
Catwoman:Two lives left. I think I'll save one for next Christmas. But in the meantime, how about a kiss Santi-Claus?
In The Black Hole, Reinhardt's robot Maximilian drives a spinning blade attachment through Alex Durant's stomach.
The 1990s version of Godzilla dies at the end of Godzilla vs. Destoroyah. He is not revived for another film, he's not faking it, he does NOT get better. It's one of the few films in the Godzilla franchise in which Godzilla dies and stays dead. Although his son (who was THOUGHT to be dead) takes his place at the end of the film.
Likewise, in GMK Baragon, Mothra, and King Ghidorah are all killed-off by Godzilla and stay dead throughout the rest of the film.
Also, the original 1954 film? Yes, folks, Godzilla dies. Even though the original film is considered canon across all continuities of the franchise, the Godzilla that shows up in any of the sequels; he's just another Godzilla. The first one really did die. Going by Godzilla vs. Destoroyah, this also means Godzilla died for good twice.
Randy Meeks: Careful. This is the moment when the supposedly-dead killer comes back to life for one last scare.
[Billy starts to rise, only to receive a headshot from Sidney.]
Sidney Prescott: Not in my movie.
Stargate Continuum: After dozens of Ba'al's clones have been killed throughout the last few seasons of the series and he has continually escaped death to return yet again, both the last clone and the original Ba'al are finally killed for good by SG-1.
An in-universe example: any video game character who dies outside of their game in Wreck-It Ralph is dead for good, as opposed to just respawning a moment later. True to Disney tradition, the only ones who actually do are the Big Bad, Turbo, and several thousand Cy-Bugs.
In Guardians of the Galaxy, Garthan Saal, an ally of the Guardians, dies while trying to hold back Ronan's ship from crashing onto Xandar. Earlier, Ronan kills Thanos's Dragon, the Other, who acted as Thanos's voice in both this movie and in The Avengers.
In Avengers: Age of Ultron, Quicksilver is gunned down protecting Hawkeye and a 12 year-old kid from an Ultron-commandeered quinjet.
Odin is also a downplayed example in Thor: Ragnarok when he also dies simply of old age but played straight with the Warriors Three when they all get stabbed by Hela.
Zuri in Black Panther gets impaled by Killmonger when informing him the truth of N'Jobu's death.
Loki in Avengers: Infinity War, Thanos remarks "No resurrections this time" when crushing his neck and Thor later tells Rocket that this time, he thinks he really is dead. Heimdall also died earlier as well.