Splicers serve as the mainstay infantry in BioShock.
These are humans who through the excessive use of ADAM have mutated into humanoids permanently endowed with various superpowers, but who are also murderously and irreversibly insane. Unlike the protagonists of the first two BioShock games, who can mix and match the powers given to them by the use of plasmids with near-limitless variety, Splicers fall into a set of different categories that give each splicer type a consistent but limited set of abilities and powers (Spider Splicers, Brute Splicers, Houdini Splicers, Leadhead Splicers).