[MatthewM]

I am not familiar with all of the characters from the earlier ages that most of you are speaking of, so I am going to answer with my obvious choice. A Man who was definitely not "stupid", although perhaps stubborn and prideful-

Boromir of the Nine Walkers, of the Third Age.

The most renowned warrior of his time, and the greatest Gondor had seen in many years. Defending Gondor on countless occassions from the growing might of Sauron, in specific his defense of Osgiliath, Boromir proved vital to Gondor's survival during the last years of the Third Age.

In addition to being the Captain of the White Tower, Boromir's death was a truly heroic one...one of a true warrior. Sacrificing himself and fighting on against ridiculous odds, only falling when numerous arrows reigned on him, shot by cowardly orcs who would not dare face him sword to sword.

I know most here will not agree, but in my opinion as far as my knowledge streches at this time, Boromir was Middle-earth's greatest warrior.