From my medium-interest-in-comics viewpoint, that seems really unlikely. The Fantastic 4 were a group that got their powers at the same time in the same accident. Sue, her husband, her brother, and their friend. They may work with other people, but the four? Just them.

But Spidey did knock about with them quite a lot, whether formally or informally. Took on Doctor Doom together, that kind of thing. Also, they play poker with him. And Angel from X Men, and a couple of other guys. I think I know about The Fantastic Four from a mixture of cartoons on the telly and, quite possibly, because they were in one of the Spidey comics that I used to read when I was wee. I remember a really really depressing plotline in which Mr Fantastic and the Invisible Girl lost their child - can't remember if it died, or what, and it all happened on some other planet/some other dimension. But it was serious marriage breakdown worthy stuff. And I was only wee, and thought at the time "blimey, comics are a lot less cheerful than grown ups would have us believe. Huh."

Spider man and his Amazing Friends (Iceman and Firestar)

Ooh! I remember them!

If they didn't mention it in the Adam West cheesefest on TV, I didn't know about it until the first film.

But Spidey did knock about with them quite a lot, whether formally or informally.

That is absolutely true. Johnny Storm was one of his earliest friends in the superhero world too.

Is it really possible to have heard of Batman and not know this?

Pretty sure a lot of Joe Q Public (as, for example, Ma and Pa Jay, Chez Fay) only associate the Bat Man with the cheesy TV show from back in the day. Primary colours, wrinkly tights, Bam, Kapow, Zoink etc etc.

But Spidey did knock about with them quite a lot, whether formally or informally.

Sure. Everyone knocked about with them. I'm surprised to learn he had been a member, even for a hot second, or that that many other people had too. Were they still the Fantastic Four when there were five of them, or did they swap people out?

I'm surprised to learn he had been a member, even for a hot second, or that that many other people had too. Were they still the Fantastic Four when there were five of them, or did they swap people out?

She-Hulk was a member, too, during a time when the Thing went walkies. Wasn't Power-Man a member briefly? And, yes, they were always 4, as they others were only replacements.

Were they still the Fantastic Four when there were five of them, or did they swap people out?

Well, they could get up to Five and still be Fantastic. If they hit Six, they had to move up to Stupendous.

I remember a really really depressing plotline in which Mr Fantastic and the Invisible Girl lost their child - can't remember if it died, or what, and it all happened on some other planet/some other dimension.

Their son was Franklin, I'm not sure what his exact story was but he was super super smart. For awhile he hung out with the Power Pack. The Power Pack were siblings (2 boys, 2 girls) who got their powers from aliens. I don't remember what their powers were but at some point all their powers got mixed between them.

Franklin! Yes! Well done!

...I'm quite endeared by the prospect of Spidey and the She Hulk etc stepping in to cover for members of the Fantastic Four when they were, what, on holiday, or on sick leave, or having a pyjama day, or whatever. Like Super Temps. Cool.

They said the same thing about Highlander II: The Quickening

Yeah, but how many movies can you argue proved them wrong about that one? Right now I'm coming up with House of the Dead and Out Cold (the ski "comedy" with Jason London, not the Clooney version) that might be contenders, and not a lot else. Catwoman looked like more fun to me.