Solid Snake

Solid Snake in Metal Gear Solid 2
Solid Snake in Metal Gear Solid 2

Solid Snake is the hero who you play as at first and for most of the Metal Gear saga.  The first time you meet Solid Snake is in the original Metal Gear for the MSX.  Snake is still a rookie at the time and has been assigned to a very dangerous mission.  His objective is to infiltrate Outer Heaven, rescue the scientist and put an end to the bipedal walking tank: Metal Gear.

 

However, he later finds out that his commander Big Boss is actually involved with the terrorists as their leader.  It is then Solid Snake's job to defeat his former mentor in a battle to the end.  

 

Of course, this doesn't mark the end for Snake. He later reappears in the rest of the series as a playable character.  In Metal Gear Solid for the PlayStation, he is known as a legendary hero for having stopped nuclear war in two separate occasions.