First Sylvester Short?
 

In the Porky Pig cartoon "Kitty Cornered" (I think that's the name), there's this cat that spits all over another cat while he's talking who looks familiar.... was this an early prototype for Sylvester? :sylvester

Actually, Sylvester as we know him first appeared in Friz Freleng's "Life with Feathers", released in 1945. The leader cat in "Kitty Kornered" (released the next year) borrows Sylvester's voice, but it isn't his first appearance. I hope this helps!:)

In the Toonheads episode Sufferin' Succotash, Kitty Kornered is identified as the only Sylvester short directed by Bob Clampett.

I agree, the cat is definitely Sylvester (listen to the audio commentary on the DVD). though the character model is closer to Bob McKimson's version of the cat (see "Crowing Pains").

However, as mentioned already, Sylvester's first short is "Life With Feathers" though he carries the name "Thomas".

Maybe Mckimson took that Bob Clampett character and molded him into his own? *shrugs*

I think you're getting confused with "Tweetie Pie" where Sylvester is called Thomas. I don't think he was named in "Life With Feathers".

Although the cat in "Kitty Kornered" was definately meant to be Sylvester, what about in "A Hick, A Slick And A Chick". A very simalar looking cat named Herman appears in that cartoon, and it was released after Davis made two cartoons with a cat that most people believe to be Sylvester. :sylvester