Promethean Crawler

Crawlers are advanced Forerunner AIs and a new class of enemies in Halo 4. They are quadrupedal in design, and are capable of both close-quarters and long-range combat, having been engineered to ferociously hunt down and eliminate any foreign threats. It is not uncommon to encounter Crawlers in substantial numbers, as most travel in large packs and work together in strategic coordination to bring down enemies by overwhelming them from every conceivable angle.

Crawler
The standard Crawler is the most common variant of the Crawler. It is able to cling to surfaces and melee the player. They are equipped with a Boltshot.

Crawler Snipe
Crawler Snipes are similar to regular Crawlers, except with an additional 'horn'-like segment and face-protection added. They are the Promethean forces' scouts and snipers, lurking and picking off their enemies from afar. They utilize the Binary Rifle and can track foes through obstacles with Promethean Vision.

Crawler Prime
Crawler Primes (or Alpha Crawlers) are the leaders of packs of Crawlers. They are easily distinguishable from other Crawlers because of their spines. They utilize the Suppressor.

Tactics

 * Crawlers act as the cannon fodder of the Prometheans, in a manner similar to Unggoy, but with their advanced agility and use of harassment tactics, they actually fight in a role more similar to the Covenant's Skirmishers.
 * With aggressive tactics, access to powerful weapons, superior marksmanship, and the ability to melee the player, Crawlers represent a much more dangerous enemy than the typical Unggoy. Grenades and kamikaze attacks are the only abilities a Unggoy has, but while a Crawler lacks these abilities, their mobility and melee capabilities more than compensate for it.
 * Although they can be taken down with a single headshot, Crawlers are actually resilient enough to shrug off several hits to the body and fight on.
 * Despite their small size, their melee attacks are very strong, so you should try to avoid close combat with them as much as possible.
 * Crawlers tend to try to overwhelm a player by attacking in groups.

Trivia

 * Crawlers are the most extensive and abundant native enemy on Requiem.
 * Despite this, the Crawler Snipers are the rarest enemy in the game. This makes making the enemy commendation for killing them very difficult. However, the third mission in the first episode has the most Crawler Snipers in any mission with 8 to 10.
 * During the demo at E3, you can see a pack of Crawlers attacking the Master Chief before he continued on. In the end of the trailer, a creature that is possibly a different rank of the Crawler, or another species entirely can be seen for a few frames.
 * Despite the Boltshot having a charged shot, Crawlers are never seen using this powerful function.
 * Cortana states that Crawlers have similar 'cortical footprints' as the Knights.
 * While Knights seem to be made from humanoids, Crawlers are more animal-like in their movements.

Appearances

 * Halo 4