One of the three surviving clones of Big Boss in the "Les Enfants Terribles" Project. Created to simulate the skills of Big Boss himself, Solid, Liquid, and Solidus Snake are the only survivors. In the first Metal Gear Solid, Liquid heads a terrorist faction to steal Metal Gear. Ultimately, he is killed by Solid Snake and Metal Gear is destroyed.
In Metal Gear Solid 2: Sons of Liberty, Liquid Snake is revealed to be alive in the form of Revolver Ocelot's right arm. Liquid has the ability to take over Ocelot's mind, but he (Ocelot/Liquid) is pretty low key in the game. At the end of the game, Ocelot/Liquid escapes from Metal Gear Arsenal in a RAY to an undisclosed location. Luckily, Solid Snake put a tracker on him (a convenient way to open up for a sequel.)