UPDATE: In honour of the AMAZING LOOKING L4D2, I'm tareing myself apart to create new bosses, uncommon common and special infected ideas for L4D, as well as a new thing called a viral strain (a series of related infected enemies with different levels of power,) and new ANIMAL INFECTED!!

Also, I'm adding loads of new Killing Floor specimens!

Also, I've added some new progress critera.

"In Progress" means that I'm still drawing it, and the percentage shows how close I am to finishing it
"Pending means that the image is 100% complete, and I simply need to upload it

While you wait for the new guys to be uploaded, why not take a trip down memory lane and look back on my previous creations?

Update 2:
I've decided to add some achievements relating to each L4D infected and KF Specimen!

Left 4 Dead

Special Infected (Examples: Smoker, Hunter)
The Vampire: [link]
The Assassin: [link]
The Arsonist: [link]
The Berserker: [link]
The Scream-O: [link]
The Sprinter: [link]
The Landmine: [link]
The Gargoyle: [link]
The Sadist: [link]

Boss Infected (Example: Tank)
The Archetype: [link]
The Cannon: [link]
The Stalker: [link]
The Reaver: [link]
The Knight: [link]

Final Boss Infected
The Trigger: [link]
The Commander: [link]
The Boogeyman: [link]

Uncommon Common Infected (Example: The Hazmat)
The Stinkfist: [link]
The Rotter: [link]
The Brutaliser: Pending
The Kamikaze: [link]
The Bouncer: Pending
The Tinpot: Pending
The Brawler: Pending

None Verses Playable Infected (Example: Witch)
The Riot: [link]
The Sheild: [link]
The Terroriser: [link]
The Drowner: [link]
The Hangman: [link]
The Maniac: Pending

Infected Strain Type:
The Cancer: Pending
The Bladed: In Progress 0%
The Taloned: In Progress 0%

Animal Infected:
The Gorebeast: In Progress 0%
The Mauler: [link]
The Hellhound: In Progress 0%
The Swarm: In Progress 0%

New Weapons: In Progress 0%

Killing Floor

Normal Specimens (Example: Gorefast)
The Gangrene: In Progress 0%
The Walloper: Pending
The Birther: In Progress 0%
The Shifter: In Progress 0%
The Defender: Pending

Specimen Varients:

-Birther-
Birther Bombspawn: In Progress 0%
Birther Spitspawn: In Progress 0%

-Clot-
The Regenerator: [link]
The Lobber: [link]

-Crawler-
The Spawner: Pending

-Bloat-
The Exploder: Pending
The Tosser: Pending
The Shunter: Pending

-Husk-
The Slagpile: Pending

-Skrake-
The Butcher: [link]
The Dismember: [link]

-FleshPound-
The Slave Driver: Pending
The Flagellator: Pending
The Soldier: Pending

Killing Floor Bosses (Example: Patriarch)
The Fortress: [link]
The Empress: [link]
The Armoury: [link]
The Guardian: [link]
The Martyr: [link]
The Phobia: [link]
The Chimera: [link]
The Devourer: [link]
The Re-animator: Pending
The Malefactor: Pending

-Martyr-
The Sunderwound: In Progress 0%
Bladespawn: In Progress 0%
Spewspawn: In Progress 0%
Lungspawn: In Progress 0%
Whipspawn: In Progress 0%
Leaperspawn: In Progress 0%
Bombspawn: In Progress 0%
Clawspawn: In Progress 0%

-Chimera-
Wolf Form: In Progress 0%
Gorilla Form: In Progress 0%
Crawler Form: In Progress 0%

New Weapons: [link]