|Go ahead, unload that entire assault rifle clip into him, he can take it.|
I was content to think of the Flood as a bunch of zombies who were controlled by the parasitic forms, each with individual mindless goals (attack anything that isn't a Flood). However, with the release of Halo 2, Bungie decided to make the Flood a hive-minded species, controlled by one supreme Flood creature. The problem is that they chose one of the most laughable ways of doing this. Meet Gravemind:
It's a little hard to tell from screenshots, but Gravemind is essentially a gigantic talking Venus flytrap. Kind of difficult taking the story seriously when something so comical is introduced isn't it? Gravemind's main goal is for the Flood to consume all sentient life in the galaxy, apparently while they all die of laughter from seeing a talking plant pretending to be a badass.
Despite all the negative feedback from Halo fans, Bungie again included Gravemind in Halo 3 as one of the main antagonists. Thankfully the Master Chief and the Arbiter destroy him once and for all, but it remains to be seen if another Gravemind-like creature will make an appearance in Halo 4.