I think mine’s Z for Zachariah. The book is insane. A psychological survivalist thriller between a 14 year old girl and a strange man with unknown intent. The movie is… not this. They changed everything meaningful about the characters and lost all the tension. Hope someone does it properly one day. What’s your adaptation peeve?
I, Robot. They literally stole the book’s title and used it for a totally unrelated story.
The Dark Tower and it’s not remotely close.
This is a fairly mild one but I didn’t like Netflix’s The Guernsey Literary and Potato Peel Pie Society adaptation. The protagonist in the book is witty and sharp and kept you reading based on her quips and humour alone, but the movie version completely saps her of her charm and personality
Night watch/Day watch. This books were amazing and dear God the movie was absolutely awful.
Eragon. No contest.