Lord of the Rings Series -- Amazon

Cannon doesn't start bothering me until they begin contradicting things that already happened/was established at some point in the timeline. The MCU absolutely didn't follow cannon because in the Infinity war comic, Nebula took the gauntlet and undid the snap and Adam Warlock was the hero because he short circuited the gauntlet from within the soul stone. Thanos absolutely brutally murdered a lot of the avengers in the comic as well.

Game of Thrones also heavily deviated from the books. Lady Stoneheart(undead Caitlyn Stark) was the one exacting revenge on the Frey's in the book. In the show, Arya Stark dealt with them.