The Crawler is a Zed created as an experiment done by Horzine. It was an attempt to cross genetics from a human and an arachnid. Crawlers spawn commonly with clots, stalkers, and gorefasts.
Crawlers move, as their name implies, on the ground. Due to this, they are easy to miss if not paying close attention. The Crawler has very little health and can be taken out with relatively small amounts of fire, depending on the difficulty. Due to their low health and their tendency to cluster into groups, weapons with high rates of fire are suitable when facing Crawlers. However, as stated before, they are often hard to spot, and they can deal a reasonable amount of damage if they are allowed to get through.
They tend to be quite annoying as they can slowly but surely tear apart a survivor's combat armor. Retreating from swarms of Crawlers are also difficult as they can fairly catch up and still attack. Moreover, they can leap a short distance, thus causing some shots to miss.