By far the most important Marvel characters of all time are the Fantastic Four. We call them the first family of comics for good reason, since without them, the Marvel universe would literally not exist and Stan Lee would have kept making tacky romance comics until he hit burnout and left. And frankly, that's not a world I wish to inhabit.
However, having such enormous shoes to fill have driven the many writers and artists that took over from Lee and Jack Kirby to make some... bold choices. Some, like the creation of the Future Foundation, are amazing and change everything about the FF for the better.
This list is not about those choices. No, this will look at the stuff that Marvel has gone out of their way to make you forget ever happened.
Whether it be because they're flat out awful or because writers just don't know what to do with the material they're continuing off from and so choose to ignore it altogether, these are the things Marvel would very much prefer you forget that the Fantastic Four were ever associated with.