Who are the 'players' in the Annihilation storyline?

Annihilus, Thanos, Nova, Starlord(formerly known as), Ronan, Superskrull, Galactus, all of his former heralds except Nova, Two other Galactus-type beings whose names escape me, Drax, Gammora, and probably a few others by now, I'm getting behind. I've heard Blastaar is making an appearance.

Yep Blastaar is in.

And it's a great read, a little confusing if you don't read the mini's but good. Also reading the Thanos 12 issue run will help along with the beta ray bill mini.

In short it's Cosmic Chaos and everyones in it.