Alien
Aliens are an insect-like species of gigantic proportions. If grown to full size, they look a lot like a Human (because it's born from a Human host, usually), but the similarities end there; the Alien, also known as the "Xenomorph," is physically many times stronger and faster than a weakling Human. It's the strongest (though not always the most durable) and fastest creature known to man.

United States Colonial Marine
Colonial Marines are well, humans. Homo-Sapiens. Earthlings. Terrans. Man. They're you; two arms and two legs. You get the idea - just go admire yourself in the mirror and you'll find out more. But these Humans we're talking about here are a little different; they're United States Colonial Marines, who've survived months of physical and mental training to become America's perfect killing machine, and they've done a Hell of a job at it.

Predator
The Predator is a humanoid creature; sporting an endoskeleton structure, large muscles and a high intelligence. But on a closer study, the Predator is bascailly the middleground of the three species; it's not as physically strong or as fast as the Alien, but it fares pretty well; it don't have such powerful weapons like the Colonial Marine, but its weapons fare pretty well. In other wods, the Predator takes the best of both worlds and places them together.

» AvP Cheats