How would you classify The Killers, The Strokes, Arcade Fire, Arctic Monkeys or even The White Stripes? They certainly got stamped that label at least early on in their careers.

I know "indie rock" is a very broad term, but I don't follow those bands closely anymore so I wouldn't know to what subgenre they belong right now. The Killers for example had more rock in the beginning but the latest albums had a stronger synthpop feeling. I don't even think The Killers make *rock* music anymore (sue me).

I don't consider Fun to be an indie rock band, but I've seen them in that group too. The line is pretty blurred nowadays because there's very little "pure" rock in mainstream radio and there's no uniformity like there used to be until late 90s. I'm not saying that's bad though, there's much more to choose from nowadays and bands can experiment with their sound, there's no "trying to fit in the commercial mold of band X and sound Y". It's not my type of rock, but I respect it, there are quite a few quality bands out there...

But if you mean indie rock = underground bands, then none of the above fit the bill. They are very very mainstream.