Inspired by the
Golden Age thread... (Marvel Zombie alert

)
Stan never creates FF, or can't get approval to run them.
Stan & Steve don't create Spidey.
Gwen doesn't die. Or MJ dies, instead.
Jean doesn't die. (This may violate the CCA...

)
The (greedy, scum-sucking) suits don't revive Jean for
X-Factor,

which never happens.
Pete & MJ don't get married.
Black Panther's origin and approach is closer to Luke Cage & the Miller Daredevil.
White Tiger is closer in approach to Miller's Daredevil.
TNT doesn't happen.
Robin never becomes Nightwing.
Iron Fist doesn't get cancelled. (Yeah, I know, ASB.

{

}) That would mean we never see him kick the X-men's asses, tho.


And how about a wild one: the '50s hysteria persuades the major comics publishers to turn crime & horror comics into full-size magazines (like
Heavy Metal), aimed at adults.
Feel free to add your own--with consequences! Or add the effects of any of these.