usually, you'd have a bunch of actors introduced in one movie. that movie becomes one big hit and spins off several franchises. the actors break up into their solo movies.
what i just LOVE about the avengers is how they did that formula backwards. iron man, thor, captain america (and to lesser extent, hulk) have had successful solo movies! and they have built up a following. so multiply that by the number of those superheroes! astounding!
i haven't been this excited over an action movie! and it is simply because it is an ensemble of superheroes! now if they could only fold in those dc superheroes! LOL