I'm sorry, but regardless of what ANYONE (Even Don Bluth) says, I just can't see Sharptooth as not being a villain. His actions in the movie just don't seem like an "instinct of nature" to me.
I'm terribly sorry, but to me, he is a villain. Bottom line. -_-
What actions in the movie did Sharptooth do that were not an act of instinct that make you so sure that Sharptooth wasn't a villain?
Killing Littlefoot's mother is an act of instinct. He's a predator; that's what predators do to survive. This action wasn't out of spite nor was it act of vengeance on Sharptooth's part.
Attacking Littlefoot and his friends is also an act of instinct. Again he's a predator. And there's not as many dinos around (due to the land now being barren) so it could be that, when Littlefoot and the others ran into him again, he was starving to the point where he was desperate for anything, even something as small as the children dinosaurs.
True, he could have been out to avenge his eye, although there isn't as strong of evidence in the movie for this. But even so, avenging an eye is not a strong qualification of a villain, in my opinion. Yes, it does make Sharptooth seem more heinous, trying to kill Littlefoot for something that was a mistake, but that doesn't necessarily make Sharptooth some grand villain.
In the end, the only action that Sharptooth does that could make him some kinda villain, that would might have been "out of nature", is him avenging his eye, which we don't know was even a strong motivation in the movie. It may have been a bit stronger in the book, but in the movie there isn't much of a hint that Sharptooth wants revenge on Littlefoot. And even if he did, how long did this vendetta last? Can we be certain that Sharptooth was so evil that he would continue to hold a vendetta against Littlefoot?
Anyway, here's my list of top 10 LBT antagonists:
10. Chomper's parents
9. Swimming Sharptooth from LBT 11
8. Dil and Ichy
7. Hyp, Nod, and Mutt
6. Pterano
5. Strut
4. Sierra
3. Rinkus
2. Ozzy
1. The Original Sharptooth
Keep in mind that though antagonists are the opposing force or a opposing force in a story, they do not always have to be evil. They don't even have to be alive; tornadoes and earthquakes can qualify as antagonists, for example.
I chose the original Sharptooth as 1 not because I consider him the baddest villain, but the scariest antagonist.