I have no real problem with D&D game design including a healthy dose of humor; the Dungeonland modules were two of my favorites from 1st edition days, and my friends from high school that I played with still occasionally reminisce about gaming and the unabashed silliness of the time we played Fluffy Goes to Heck still elicits a chuckle. So that aspect of Hecataeus (while certainly nowhere near as extreme as either example) doesn't turn me off like it does some. Sure, he falls into some intentional 'evil wizard' stereotypes, but it's done intentionally enough and tongue in cheek enough to make him fun and memorable. Less so and he would have been cliche, more so and he would have been a self parody. I think you got it just right. The D20 equivalent of the DC villain Dr. Light. (Well, before the decision was made to make Dr. Light competent and dark, but I'm doing a cross-geek digression.)
I have no real problem with him; though it could be said that his hooks lack a little 'oomph' to bring him fully into conflict with the PCs. (Although the intelligent item one gives me a fit of the giggles. I'm imagining a confrontation between the PCs, holding the item, and Hecataeus himself, and the item and the wizard snarking back and forth at each other while the party grows increasingly disgusted and annoyed.) Probably because most of your text had to go to personality. Fortunately, that was a worthwhile investment; the writing and the personality are what makes this character shine, moreso than if you'd spent an extra paragraph or two describing his army of constructs or the like.
He gets my vote, based on sheer force of personality and fun. Seeing his stats should be interesting; you've proved your writing chops here, seeing how your command of mechanics measure up will be a treat.
Seems like people are really divided on the plot hooks for this character. I like them myself. It appears that this character is going to make his way into some home games based on this submission. There has been a lot of discussion regarding what defines a quality submission; when I think about it isn't the fact that the character is going to be utilized by some readers quite telling in itself? I can't think of any better indicator. Based on that this character grades high.
I just want to thank everyone again who read through my entry and took the time to post in this thread. I will certainly take all input (good, bad, and ugly) into consideration going forward.