The Licker is one such mutation experienced by zombies as part of the V-ACT process, depending on the variant of the t-Virus they were infected with. The mutations transform them into deadlier, more agile hunters.
During the outbreak, a potent variant of the t-virus infected the water supply at the Apple Inn hotel, creating a large number of the creatures.
In the 21st century, the Licker was reexamined by Tricell, who modified the creatures with further viral infections to create a more powerful weapon. These mass-produced replicas, the Licker β, were also employed by rebels in the Eastern Slav Republic to fight against the armies of Svetlana Belikova, and were controlled using Plaga parasites.