9. Invisible Woman's Powers
For the most part in comics, a fan backlash usually occurs after a change has taken place. In the example of Sue Storm, though, the backlash came because of how much that character needed to change.
When the Fantastic Four were first created by Stan Lee and Jack Kirby, Sue's Invisible Woman act saw her with the ability to render herself invisible at will. But after the first few adventures of Marvel's First Family, readers felt that Sue was a useless afterthought in most of these missions.
This was at the time when the likes of Lee and Kirby were keen to address fan letters in the actual comic books themselves. Seeing the outcry of negativity towards the Invisible Woman, this matter was originally addressed by the FF retorting that Sue was the inspiration behind the group, and how she supported the other three members of the team in the Fantastic Four's battles.
That response from Lee and Kirby was a lame one that didn't wash with readers, and so change was on the way for Sue Storm.
That change famously came in Fantastic Four #22, when Sue's powers were expanded on to allow her to manipulate invisible force fields and also be able to make others invisible. Skip forward a few years, and the Invisible Woman was soon one of the most powerful heroes in all of Marvel Comics.
Were it not for that early fan backlash though, who knows how things would've played out for the Invisible Woman.