Ursula From The Little Mermaid
Ursula is a sea witch, which any marine biologist will tell you means "eight-legged obese mermoctopus." After the movie's heroine, Ariel, meets Prince Eric ("Eric"? Really, Disney?), she decides that she absolutely must become human, probably due to the limitations of human/mermaid sex. Ursula gives her a set of legs in exchange for her voice. Being evil, she makes the trade at the bottom of the ocean. Ariel becomes human and almost drowns, barely managing to make it to shore, and Ursula, who's somehow a heavy smoker, cackles raspily because she totally saw that shit coming.
The Horrific Death:
Near the end of the movie, Ursala blackmails Ariel's father, King Triton, into giving her his magical trident, the One Ring of The Little Mermaid. This allows her to transform into a giant super-Ursula and control the weather.
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Eric (ugh), deciding that he's had quite enough of this shit, steers a ship through a whirling vortex of doom and uses its bowsprit to freaking impale Ursula right through the gut.
Walt Disney StudiosUh ... we think ...
For whatever reason, this causes lighting to strike her for an effective electro-stab combo. If they'd only stuck an explosive in her mouth, they would have covered the shark kills from all four Jaws movies.
Ursula screams in agony and falls back into the ocean, the saltwater and electricity searing through the massive open wound in her belly and charring her huge, exposed intestines (that last part is implied but not shown). The horror of this fresh in everyone's mind, the king gets his trident back and makes everyone happy and everything better, somehow. Is there no problem a large-scale impalement can't solve?
Scar is King Mufasa's brother. He not only conspired against and subsequently killed his own brother, but also tried to kill his nephew and (presumably) boned his late brother's wife. This is the sort of thing that goes on all the time among lions, but nobody makes a fuss until they start talking.