X-Men Origins: Wolverine

The clearest skip in the franchise, and the one the series spent a decade apologising for. Every subsequent film contradicts it: First Class recasts and relocates characters it introduced, Days of Future Past wipes the timeline it sits in, and Deadpool opens by mocking it directly.

The production was notoriously troubled, including an unfinished workprint leaking online a month before release, which meant a substantial part of its audience watched a version without completed effects. The finished film does not look markedly better: the claws are visibly rendered in several shots and a widely mocked bathroom scene has become the standard example.

What it does to Deadpool is the part people cannot forgive. A character defined entirely by talking is introduced, played by the right actor, and then has his mouth sewn shut and is turned into a silent composite with eye beams and swords in his arms. Ryan Reynolds spent the following seven years campaigning to undo it and the 2016 film opens by killing that version.

The first five minutes, a credits montage of two brothers fighting through a century of American wars, is genuinely good and is the only part worth your time. Nothing requires it.