So Vincent Proce, one of the artists for MK vs. DC Universe, has updated his page with tons of goodies from this game.

Check out all the never-before-seen sketches, paintings, early box art mock-ups, and transitions of the characters endings as they are shown from a rough black-and-white sketch to the final version shown in-game.
He also gives credit to his fellow artists Bruno Werneck and Mike Tassie when applicable.

To view the artwork directly on his page, click here. Thanks to samus_aran3900 for another update!

Update: There's also this illustration he's posted, of many video game characters, including Scorpion:

In addition – and thanks go to queve for pointing this out – he's also posted the complete storyboards from the first chapters of the MK side as well as the DC side of MK vs. DC Universe's Story Mode. Here's DC:
And here's MK:


Update (Sept-20-2009): Vincent Proce has also updated his blog with some more stuff. From his blog directly:

Here are the never before seen Mortal Kombat characters I designed for a Mortal Kombat pitch I made before I left Midway last year. The basis for the idea was a re imagining of the Mortal Kombat franchise from the original premise but mixing modern muti-player and dismemberment game design with the original fighting mechanic.

I also took the original character designs and upgraded them.



Scorpion as a wraith wearing the yellow blood of the demon that helped him resurrected to exact his revenge against his mortal enemy.

Raiden as a god who's feet rarely touch the ground.

Sonya, the daughter of a Texas Ranger who's sex appeal weakens her opponents while her Special Forces training kicks their asses.

Kano, half Japanese half US military bad ass.

These are the only four characters I designed and presented with the pitch. The game idea isn't going to happen now that I no longer work there. I still would like to one day redesign all the rest of the original characters if I ever find the time.

Update (Mar-21-2010): Vincent also updated his blog to say the following:

Hello folks, I promised that I would try and complete the other five characters from the original Mortal Kombat when I found some time and yesterday I did. Here is Sub Zero how I envision him. I haven’t worked out much of his back story other than that he was a part of the Way of the Frost Dragon, an honorable secret society of warriors that were direct enemies with the ninja organization Scorpion was a part of before he was killed by Shang Tsung (disguised as Sub Zero).

Over time I will try and draw the rest of them.

Sub Zero was always my favorite character to play with.