Liquid Snake is Solid Snakes evil Twin brother. He joins this mission in all, to gather information and weapons from the government by threatening to launch a Nuclear strike. He is considered the Leader of the Terrorists and is often referred to as Boss. Liquid knew of his and Solid's horrible past, and upon bringing Snake their tells him everything about their birth.

Their Birth: Liquid and Solid, where cloned from the cells of Saladin or Big Boss, and infused with a egg of a female's uterus. Initially 8 clones were created, but 6 of them where forcefully aborted, to allow the last two to feed upon their nutrients. Doing more experiments, the doctors made Liquid carry all the recessive, while Solid Snake attained all of the Dominant Genes. Liquid from their was told by their father of his inferiority, and had started hating Solid Snake since childhood. He is eventually killed by FOXDIE, but is brought back, as Ocelot's right arm.