The Demoman = Demolitionist

He is dressed like a "Thrasher" type with a dirt bike helmet.
The Engineer

He is mainly a builder
The Medic

Lets make him a little "Retro" with some type Ray-Gun Healer vintage 1950's
The Spy

lets make him look like a Spy! I didnt like the direction Valve went with him.
The Scout

Lets make this Character a Female, I live in Chicago, there's alot of female joggers in my neighborhood, and most of them are quick and sexy, and terribly distractive. This could work well in the game. as a Distraction.
The Soldier

Not too much design on this one, I just went with the pencil.
The Sniper

Just a sniper, not too much design on this one either.
The Pyro

Here's the pyro, a little different than valve, and all designs are not coppied.
The HW Guy

I just threw this one on the paper, I was just running out of ideas.
I leave The floor to you guys, to come up with more designs and "IDEAS"
These are just My Ideas and would love to bring Team Fortress to Nexuiz.
Nothing is written in "STONE" these are just Ideas...
EDIT: **The Part Below**
Tzork Said: Tough your drawings are good; it does seem like a total tf2 copy. I suggest you use your vivid imagination to dream up some new classes instead

I have Been Doing a Little BrainStorming on My Own, and came up with a couple "Ideas".
How about a "Trapper" a guy that Makes "Traps" he'll be 'Kinda" like the Engineer, as when the engineer wants to make a "Turret" in a "Impossible" Spot for the game Engine to handle, the "Trapper" will be the same. An "X" will highlight on the HUD when he wants to make a Trap that the Engine cant handle because of bad geometry.
A Clown Type Character Called a "Klown" that make weapons out of Balloons. With Floppy shoes, and an Invisible Dog (Holding the Leash).
The Burly Brawler = No Projectile weapons, Kinda Like "Conan The Barbarian" , running around with two swords and a Shield. Speed and agility will compensate for the lack of Bombs and Missles.