Anyone who has picked up a Marvel comic book in their lifetime knows that the members of the Fantastic Four are Mister Fantastic, the Invisible Woman, the Human Torch, and the Thing - but the roster of Marvel’s first family has at times expanded over the years. Obviously, becoming an official member of the FF is one of the highest honors one can achieve in the 616 universe, so there are some pretty stringent rules about who truly “counts.”
To qualify as an official member of the Fantastic Four, one has to have been on the squad alongside either Ben Grimm, Johnny Storm, or Sue and Reed Richards, which means that the “New Fantastic Four” briefly formed by Spider-Man, Wolverine, Hulk, and Ghost Rider doesn’t count - Spidey would have to wait a few more decades to join the real roster. The definitive list also doesn’t contain young Franklin or Valeria Richards, who have long been members of the ancillary “Future Foundation,” but never members of the Fantastic Four proper - after all, it would be pretty irresponsible parenting to include children on a superhero squad, no matter what the X-Men might tell you.
What Was Her History With The FF? Soon after meeting the FF alongside the rest of the Inhumans, Crystal began a romantic relationship with Johnny Storm and stayed his long-distance girlfriend for several years thereafter.
Why Did She Join? Crystal moved to New York and joined the Fantastic Four as a temporary replacement while Sue Storm was pregnant with her first child. Eventually, she was forced to move back to Attilan for health reasons.
When Did She Join?Fantastic Four Vol 1 #132 (1973)
What Was Her History With The FF?Medusa started out as a member of the villainous Frightful Four, but after overcoming their manipulations, she became a steadfast ally of the FF - and then a family friend when her sister Crystal started dating the Human Torch.
Why Did She Join? Ostensibly, Medusa joined the team as part of a goodwill mission on behalf of the Inhumans, but she conveniently chose to do so after Sue and Reed Richards had a nasty spat that resulted in Sue leaving the team for a while - making Medusa more or less a temporary substitute. She would return to the team years later.
When Did He Join?: Fantastic Four Vol 1 #168 (1976)
What Was His History With The FF?Luke Cage met the FF during an amusing adventure in which he borrowed their plane, flew it to Latveria, and beat up Doctor Doom - all because Doom owed him $200.
Why Did He Join? With Ben Grimm seemingly permanently cured of being the Thing, the team needed a replacement, and so they called on the Hero for Hire, Power Man. Within an issue, however, Cage had been possessed by the Puppet Master, necessitating Grimm becoming the Thing again to save the day and take back his roster spot.
When Did She Join?Fantastic Four Vol 1 #177 (1976)
What Was Her History With The FF?Greer Grant had teamed up with the Thing in Marvel Two-in-One #19, where they took on the Cougar in his only appearance.
Why Did She Join? Tigra initially joined the Frightful Four, but only as a Fantastic Four plant attempting to get inside info on the evil quartet. Though she was never officially announced as a new member, Grant stuck around for almost a year - including a period of time when Reed Richards was secretly replaced by an evil version of himself from “Counter-Earth” - so she was definitely part of the team.
When Did She Join?Fantastic Four Vol 1 #177 (1976)
What Was Her History With The FF? Born in a distant future ruled by women, Thundra came back in time to join the Frightful Four - only to betray them and become a tentative ally of the benevolent FF.
Why Did She Join? Like Tigra, Thundra attempted to infiltrate the Frightful Four to free Sue Richards and the crew from captivity, only to wind up captured herself. After breaking free with the team, she hung around and went on missions with them for several issues - during the same nebulous period that Tigra was sort of on the team and Impossible Man was acting as an official advisor. That’s enough to qualify her for membership.
When Did She Join?Fantastic Four Vol 1 #238 (1982)
What Was Her History With The FF?Frankie Raye was yet another of Johnny Storm’s girlfriends, who just so happened to possess similarly fiery powers.
Why Did She Join? Johnny simply asked Reed Richards if Frankie could join the team as a probationary member, and Mister Fantastic agreed, making her the first non-replacement addition to the FF’s roster. She eventually settled on the codename Nova, but she also decided to leave the team to become a Herald of Galactus.
