Lickers (リッカー,rikkā?) are mutant humans that result from a second set of mutations experienced by Zombies, in particular those who have consumed large quantities of biomass to sustain their metabolism. Lickers are noted for their large, exposed brains, lack of skin and eyes, extreme sensitivity to sound and their eponymous tongues. They should not be confused with Crimson Heads, mutants which are the result of a separate t-Virus strain undergoing the similar V-ACT process.
The earliest known Lickers appeared in the second half of 1998, and mutated from Zombies infected with an unnamed t-Virus strain which was a further modification of Epsilon. Lickers were kept as test subjects at Umbrella's NEST facility beneath Raccoon City, and a modified version was created there.
When the modified ε strain at NEST leaked out of the facility on the night of 23 September, it contaminated Raccoon City's drinking supply and infected tens of thousands of people who, therefore, were capable of mutating into Lickers. An apparent colony of Lickers emerged at the start of the outbreak at the Apple Inn, a hotel that had caught fire. Another colony emerged at the Raccoon Police Station, which was besieged by Zombies and became another colony for Lickers. Other Lickers were encountered on Sheena Island in November 1998, which may have been citizens infected with the same modified ε strain or otherwise escaped test subjects.
In the years following, interest in Lickers as bio-weapons developed amongst the black market producers. By 2009, TRICELL was already producing a cloned species of Lickers enhanced further with a Progenitor Virus infection. Another supplier gave President Svetlana Belikova of the Eastern Slav Republic cloned Lickers implanted with Plaga parasites, which could thereby be controlled by humans parasitized by the dominant species.