* LexLuthor was originally drawn with [[EvilRedhead red hair]], but was abruptly changed to [[BaldOfEvil bald]] after an artistic mistake by illustrator Leo Nowak. Not only has it stuck with Luthor's popular image ever since, but was indirectly responsible for Luthor taking the Ultra-Humanite's place as Supes' arch nemesis as DC didn't want two bald mad scientists battling Superman (and thus Ultra-Humanite gained his trademark tendency to BodySurf and was PutOnABus for several decades).
* During one arc of ''ComicBook/{{Invincible}}'', [[spoiler: Omni-Man]] marries an insect-like alien, and there's a panel of him kissing her and Invincible looking disgusted. According to the sketchbook in the back, the artist made this as a joke and Robert Kirkman decided to keep it in the actual issue.
* ComicBook/{{Wolverine}}'s iconic mask was due to this trope - when he joined the ComicBook/XMen in ''Giant-Size X-Men'' #1, he was meant to keep the same mask design that he had when he first appeared in ''ComicBook/IncredibleHulk'' #181. However, the person who drew it, made the ears and eyes too wide. However, when it was shown, they thought that it made him look like Franchise/{{Batman}} and was kept in.