LIGHTNING
She Will Destroy The World

The main character of Final Fantasy XIII and her name is actually a sham. "Lightning" is but a mask for her real name, and is the code name she goes by to keep her true identity off the records.

She does not like to talk about herself or her past but remains mentally and physically strong and independent. Lightning is well toned and quite the acrobat, as seen in the trailer, and not that surprisingly (based on her portrayal in the trailer) is not sweet. Square Enix has compared her to a noble soldier, as she is one strict gal.

Weaponry wise, Lightning uses a transformable sword/gun.

Snow
Haz Big Shoes

Snow, formerly known as Mr. 33cm for the size of his boots, is said to be big enough to carry two people at once, and run at same time.

He's seen in the trailer saving Lightning from enemy troops as he pulls up on his Shiva motorcycle. He's described as having a wild fighting style, but in the trailer he simply looks to be firing an enemy gun. Was reveal not to long ago that his full name is Snow Villiers.

Oerba
A Little Known Fact

The only known fact about this character is that she is a L'Cie, of which nothing is known what even that means really. She wears tribal-esque clothing and is seen in Pulse. Her full name is Oerba Dia Vanille