User blog comment:TheVision185/Mavel: Avengers or not?/@comment-407896-20121104114259

1/4 of the FF is not an Avenger. Namely the Human Torch. All other members of the Four have been Avengers at one time or another. But certainly not all Marvel Heroes are Avengers. It's not the Justice League after all (they gave their little communication things to every Hero around the time of Underworld Unleashed making all of them members to a certain degree).

Most of the X-Guys aren't Avengers either. Beast, Wolverine and Storm. That's it. Not counting Quicksilver who worked with X-Factor after he's been an Avenger. As far as the X-Guys are concerned I yet have to see the events after AvX.

More or less obscure characters like the Microns/Micronauts or the Spaceknights and the Infinity Watch i. e. aren't Avengers either. So, there are a lot of people in Marvel Comics who never were Avengers up to this point.