Promethean Crawler

Crawlers are advanced Forerunner A.I.s and a new class of enemies in Halo 4. Despite being quadrupedal, they are capable of both close-quarters and long-range combat, having been explicitly 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 Snipe
Crawler Snipes are similar to regular Crawlers, except with an additional 'horn'-like segment and face-protection added.

Alpha Crawlers
Alpha Crawlers are the leaders of packs of Crawlers. They are easily distinguishable from other Crawlers because of their Hardlight spines. They utilize the Z-130 Suppressor.

Trivia

 * Crawlers are the most extensive and abundant native enemy on Requiem..
 * 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.

Appearances

 * Halo 4