Exit The Exquisite Elemental

Tell me--how many people do you count on this team?

Back when comics milestones at Marvel actually meant something, readers of Fantastic Four were treated to this little gem:

It was the first 100th-issue comic celebrated by Marvel--and it featured an all-out brawl between the FF and their greatest enemies, the result of a plan cooked up by the alliance of the Puppet Master and the mad Thinker. Of course, it didn't match the massive swarm of enemies who descended on Reed and Sue's wedding in the book's third annual--but it did feature the FF fighting their enemies alone, whereas in the annual they were joined by just about every Marvel hero in existence.

And issue #100 would have hit it out of the park in that regard, except for the presence of a virtual powerhouse in the FF's ranks at the time:

Crystal, Johnny's girlfriend, was practically a fifth member of the team, and it didn't sit well at all with the book's readers. She'd offered to replace Sue Richards when Sue became pregnant, though at first Reed was reluctant to let her on the team. But his reservations vanished when Crystal demonstrated her massive abilities in battle against the Wizard in Fantastic Four #81:

Yes, that crack from the Wizard about "one mere female" stands out, doesn't it.  In late 1968, when this story was published, I'm sorry to say that probably no one batted an eye at it.  I don't know whether Wiz is referring to Crystal's power level in a woman's body or just that a woman was able to aggressively (and effectively) put the smack-down on him, though either point of view would rightfully get him an earful these days.  Regardless, Crystal isn't Sue, taking her cues from Reed, so the Wizard isn't finished being educated yet:

 
By the time of issue #100, Sue had since returned to the team. But since Crystal was still dating Johnny, she was still joining the FF on their adventures. Yet fans of the book began wondering if, instead, it was Sue joining the FF on their adventures, as Crystal's presence often tipped the odds in the FF's favor. At the time, Sue's use of her powers still involved stealth with her invisibility and limited use of her force fields (mostly for protection against attacks). She almost never took the initiative, whereas Crystal never waited to take action--and Crystal's more dynamic abilities made Sue appear invisible in more ways than one.

So when the odds were against the FF in their 100th issue, it was Crystal who turned the tide again and again--taking out both Dr. Doom and Kang the Conqueror by uprooting a redwood on them, disposing of the Frightful Four and the Red Ghost's super apes, blasting the Sub-Mariner and his entire army out to sea, and saving the team from falling after their aircraft was blasted. And all the while leaving readers wondering, "Isn't this the Fantastic Four's anniversary issue?"

One reader put it this way, in a letter to the comic about the 100th issue:

"But the thing that really bugged me was the presence of Crystal. There she was, fighting with the F.F. in their Centennial mag. I think you seem to forget what her main purpose was--to replace Sue while she was in the hospital, not to make the group the Fantastic Five (perish forbid!). I hope to see her out of her costume and back with the Inhumans, for at least part of the time, in the future."

By the time that letter was printed, it seemed a plan was already in the works to remove Crystal from the team. For in the next issue, she began to have fainting spells--and Reed determined that her inability to adjust to pollution levels outside the Great Refuge would put her life at risk if she didn't return there. Her departure not only served to restore the status quo, but also to throw a little spotlight on Johnny, who naturally didn't take the news well. Crystal was arguably "the one" for Johnny, despite the pairings that Marvel has put both of them through since that time--but there's no question that fans didn't feel the same way about her presence as part of the Fantastic Four.

Crystal's FF membership, of course, set a precedent for many subsequent shake-ups of the team, none of which had the same dynamic as the original four. It's a lesson Marvel never quite learned about this book. "Fantastic Four" isn't simply the title of this comic book--the presence of the number locks in the concept of the original four members in the minds of readers. So no matter how a story tries to spin the introduction of a new member of the Fantastic Four:

It eventually becomes clear that the characters are the only ones happy about it.