Appearing first in Resident Evil 2, the Licker is a further mutation caused by the V-ACT process, which mutates normal Zombies into the extremely agile and vicious Crimson Head. The name "Licker" was given to this creature by the officers at the Raccoon Police Department for their incredibly long tongues.
Other changes from normal Zombies to Lickers are brain swelling and becoming visible, an increase in muscle development, and the total loss of skin. This new muscle tissue allows them to do many things that normal Zombies and even Crimson Heads cannot. They can jump incredible heights and distances and move much more rapidly while their warped bone structure makes it more suitable for them to crawl about on all fours. The Licker also uses its talons (elongated from the Crimson Head stage) to scale vertical structures and ceilings with ease. This allows the creature to use predator tactics to surprise their prey. These new hunting strategies also showcase its increased primal intellect. Finally, its elongated tongue was shown to be enormously powerful, capable of piercing human flesh and often being used to decapitate its prey. Although naturally quiet and a master of ambushes, the presence of a Licker can often be hinted at by the sound of their raw flesh and claws scraping against whatever surface they happen to be crawling along, as well as a sibilant hissing sound. When attacking or incurring damage, a Licker will also make a variety of screeching sounds, producing a particularly agonized scream when killed.
Lickers have lost the use of their eyes entirely and cannot track prey by sight. Their super developed hearing however more than compensates for the loss. Upon detecting potential prey it will attack full force with teeth, tongue and claws, often alerting others of its kind in the vicinity as well. Weapons that emit very little sound, such as the bowgun, are especially useful against these blind B.O.W.'s.
There has also been confirmation of a further mutation of the Licker in the Raccoon City Underground Research Facility. It differs from the regular Licker in colour, durability and claw size. However it appears to have very similar intelligence to normal Lickers, as its attack patterns are similar, however this Licker appears to be even sharper at detecting prey and much harder to sneak around. It is a theory that these creatures were augmented by Umbrella scientists in an attempt to create an even deadlier version of an already formidable being. Both Licker types were also present during the Sheena Island outbreak.
A Crimson Head in the midst of its transformation into a Licker was encountered by a group of survivors in in the Apple Inn during a fire. This creature was dubbed the Regis Licker or Suspended. The subject was clearly a woman prior to infection judging by the remaining clothes, features and body shape, despite the half-transformed shape. It did not yet have the ability to decapitate its prey using its already mutated tongue, but displayed the ability to use its tongue as a whip against attackers.