[Shnubble]

What is it with you and your polls?
Why do we have to follow and discuss arbitrary rules to get a highly debatable best x of all time?
Why can't we have just a discussion about adventure heroes and maybe NPCs like ADan and others suggested? So far there is nothing really "optional" about this poll you are going on about and I just don't see the point of it.

Personally I agree that there is some kind of (funny) adventure-hero-archetype.
The slightly socially awkward "teenager" (even if he is actually older) who gets constantly into trouble, even if he means well. (But in the end will save the day nonetheless.) He might be depressed by his constant problems at times but more often than not he shows a borderline narcissistic self esteem. As a bonus he might also grin at the camera from time to time and share an in-joke with the player.
Simon the sorcerer is another example of this kind.

As for my favorites: (The usual suspects.)

Guybrush Threepwood (as one of the fathers of the hero-type described above. At least in adventure games. In books and movies we have met him many times before and be it just as the awkward sidekick. )
Gabriel Knight
Manny Calavera
Rincewind (though of course he is a book character in the first place. Also I have to say that he lacks personality if you compare him to Vimes for example.)
George Stobbart
With Indy it's hard to say because he also is no "original" adventure character.
I like him in the games but I already liked him before even starting the game.

Some newer ones:
Sissel from Ghost Trick is surely one of the more interesting characters.
(And be it just by the mystery around him and the way his character is slowly built up. At the same time he qualifies as a kind of anonymous hero.)

Wilbur Weathervane has some traits of the "adventure-dork" but also features a heart-warming naivety and takes us on a exemplary journey from the little to the big.