!! The 1994 cartoon:
* TheOtherDarrin: A coupleómost notably, Doctor Doom and the Human Torchóbut nowhere near as extreme as what ''WesternAnimation/IronMan'' went through.
** ''Three'' people actually voiced Doctor Doom during the series' run.
** Creator/BradGarrett replaced Creator/RobPaulsen (from ''WesternAnimation/SpiderManTheAnimatedSeries'') as Hydro-Man.
* WhatCouldHaveBeen: Plans for a third season included Sue's pregnancy (with She-Hulk or Medusa filling up the vacancy) and the return of the Sub-Mariner.
** And probably we've seen the return of Puppet Master, and find out where he's been.

!! The comic book:
* WhatCouldHaveBeen: According to Stan Lee's [[http://zak-site.com/Great-American-Novel/images/1-5/synopsis1.jpg initial]] [[http://zak-site.com/Great-American-Novel/images/1-5/synopsis2.jpg plot]], published in ''Fantastic Four #358'', Sue was originally permanently invisible, and she'd be more or less an InvisibleStreaker.
* During Creator/ChrisClaremont's run on the title, he had initially planned for [[Comicbook/XMen Kitty Pryde]] to be a recurring cast member, serving as a live-in nanny for Franklin Richards (this took place shortly after ''Comicbook/{{Excalibur}}'' was cancelled). Then-editor of the X-Men franchise Bob Harras wanted Kitty back in the main X-Men team.