The Flood Forms

The Flood Juggernaut is the name of a large Flood form found encoded in the Halo 2 disc.

The Juggernaut has two extremely large tentacles that can kill the player with only one hit. Some have spikes on their tentacles. They also can jump much higher and further than the regular Combat Forms.

Shielde carrier forms are a variant of Flood Carrier Forms with Jackal Point Defense Gauntlets.

The Flood Infector Form is a Flood Pure Form that was cut from the retail version of Halo 3 and appears only in The Art of Halo 3 book.

The Flood Ranged Form is a type of Flood Pure Form from Halo 3. It is formed when a Flood Stalker Form is damaged or chooses to mount itself in a stationary position either on the walls, ceiling, or, with less frequency, on the ground. It has a mouth-like protrusion that opens up to reveal a living missile platform of regenerating spikes. These spikes will relentlessly pelt the player if exposed. They also exhibit a behavior unlike any other in the Flood arsenal. When fired upon these forms will curl up to shield their heads, their weak point. To fully disable them the player must stop firing until they reveal their weak point once more, or continue firing until they die, regardless of their defensive posture.

Tank Forms are large and easily spotted. Unlike the other Flood Pure Forms, they can not climb on walls and ceilings. These Flood can take a tremendous amount of damage and can kill you in one hit in higher difficulties. They also occasionally spew Infection Forms from their 'mouths'.

The Flood Stalker Form is a crustecean-like Flood Pure Form that specializes in stealth and agility. It is apparently made from the re-casted bones of dead enemies. It will frequently mutate into either a Ranged Form or a Tank Form when the need arises. This form sits low beneath your field of view and their attacks can go widely unnoticed until you look down. They are able to crawl on walls and ceilings with ease, and are capable of doing enormous jumps much like combat forms. A possible flaw in its AI is that it has been observed to rarely attack players, and normally prefers to mutate itself into one of the two other Pure Forms.

A Flood Combat Form is a vertebrate suitable for combat that has been infected by the Flood parasite via an Infection Form. The victim is mutated into a combat unit that fights for Flood goals and objectives. They coordinate attacks on certain enemies by a Gravemind, if there is one.

The Carrier Form is a type of normal Flood form primarily used to both create and transport Infection Forms thus effectively spreading the Flood infection.

Very little is known about the Proto-Gravemind, also known as a Brain Form. Unlike other Flood Forms, it is apparently immobile and passive in combat. They have never been observed to move on their own, even when other Combat Forms are fighting nearby. They have never been observed to keep any of their hosts' or weapons. They use some of their hosts legs as feet and you can slightly see some of the hosts' bodies, albeit deformed. They also have not been observed being damaged by small arms fire, although small bits of flesh and Flood matter will come off. It's unknown if this causes the Brain Form any significant injury.

The Gravemind (Inferi Sententia, meaning "Thinking Dead") (voiced by Dee Bradley Baker) is the greatest stage in the life cycle of the Flood, and one of the main antagonists of the Halo series. When it reaches a certain critical mass, it develops a centralized intelligence. It is the Flood personality, controlling all other Flood forms and often speaking through them and even its hosts. It carries with it the genetic memory garnered from millennia of feasting and slumber, making it virtually omniscient. Since the intent of a Gravemind is to consume and absorb every sentient creature in the Galaxy, it is the collection of fallen Flood and other lifeforms. The Gravemind has complete control over other forms of Flood and can even speak through the Pure Forms and some Combat Forms, using this ability to taunt its enemies. The Gravemind produces quadrillions of Flood spores.

Prophet Form is a term fans have created to describe the Covenant Prophets that have been infected and overtaken by the Flood. Due to their unusual nature, they are not thought of as Combat Forms in the way infected Humans, Brutes and Elites are.

It is also worth noting that all "Prophet Forms" seen had only just been infected, and may not have been assimilated in the conventional way. The only Prophets to be seen being infected by an Infection Form were two of the three Prophet Hierarchs: Mercy and Truth. However, the Master Chief removed the Infection Form from Mercy, killing him, and Truth was killed by the Arbiter in Halo 3 before the Infection Form could complete the infection process. The Prophet of Regret became one with the Gravemind.

Flood Swarms are the first flying incarnation of the Flood yet seen, and are featured in Halo Wars.These creatures travel in large airborne packs, and can emit barb-like projectiles to puncture enemies. They are relatively weak, but can easily dispatch most unprepared infantry. These flood units are used in multiple instances to either protect much larger forms or attack the player's base.

The Bomber Form appears to have an abdomen similar to the head of a Flood Carrier Form, and this is likely where they incubate their Infection Forms. It is also probably where they hold whatever keeps them in the air, probably a lighter-than-air gas, it has two arm-like tentacles coming from the sack on either side of the 'head', and many tentacle-like appendages coming from the 'mouth'.