The Lion King
https://www.rd.com/culture/lion-king-alternate-ending/
https://en.wikipedia.org/wiki/The_Lion_King

The Exorcist III
https://film.avclub.com/just-in-time-for-easter-we-revisit-the-exorcist-and-it-1798245518
https://en.wikipedia.org/wiki/The_Exorcist_III

Casablanca
https://en.wikipedia.org/wiki/Casablanca_(film)
http://www.tcm.com/tcmdb/title/610/Casablanca/alternate-versions.html

Dodgeball
https://en.wikipedia.org/wiki/DodgeBall:_A_True_Underdog_Story

Pretty Woman
https://en.wikipedia.org/wiki/Pretty_Woman
http://www.denofgeek.com/uk/movies/pretty-woman/48793/the-original-ending-of-pretty-woman-was-seriously-dark

Alien
https://io9.gizmodo.com/the-original-ending-of-alien-was-both-terrifying-and-a-1793964487
https://en.wikipedia.org/wiki/Alien_(film)

Pretty in Pink
https://www.huffingtonpost.co.uk/entry/pretty-in-pink-celebrates-30-years_us_56c5f4d0e4b08ffac127e1a8
https://en.wikipedia.org/wiki/Pretty_in_Pink

The Birds
https://en.wikipedia.org/wiki/The_Birds_(film)
https://www.shmoop.com/the-birds/ending.html
28 Days Later
http://zombieflicks.wikidot.com/28-days-later-summary
https://en.wikipedia.org/wiki/28_Days_Later

Return of the Jedi
https://en.wikipedia.org/wiki/Return_of_the_Jedi
http://www.digitalspy.com/movies/star-wars/news/a818249/star-wars-return-of-the-jedi-alternate-ending/
https://www.cinemablend.com/new/Why-Harrison-Ford-Wanted-Han-Solo-Die-Return-Jedi-100887.html