[Keeper of Dol Guldur]

In mythology and legend, a man, often of divine ancestry, who is endowed with great courage and strength, celebrated for his bold exploits, and favored by the gods.

That would almost certainly be Aragorn

A person noted for feats of courage or nobility of purpose, especially one who has risked or sacrificed his or her life.

These are Boromir's and Theoden's parts. Gandalf also falls into this category in some degree, but also into the next.

A person noted for special achievement in a particular field.

A man of distinguished valor or enterprise in danger, or fortitude in suffering; a prominent or central personage in any remarkable action or event; hence, a great or illustrious person.

All of the Fellowship fall into this category, most of all Frodo because of the remarkability of his actions. (It's more surprising that a little Hobbit took the ring to Mt. Doom than if somebody like Aragorn had been selected).

A man distinguished by exceptional courage and nobility and strength.

Everyone in the Fellowship had their moment of exceptional courage and nobility and strength.

Someone who fights for a cause.

Again everyone in the Fellowship fights for the salvation of the free peoples of Middle Earth.

A being of great strength and courage celebrated for bold exploits; often the offspring of a mortal and a god.

Aragorn again, his ancestry being one and the same as Elrond's and of lineage of Melian the Maia, a demigod, and many great men and elves.

All of the members of the Fellowship, and those very important people that befriended them (Theoden, Eomer, Eowyn, Imrahil or Faramir), were definable as heroes, though not always in the same regard, or for in the same specific category of hero. However, as far as the classical three heros, they are fairly obvious out of the Fellowship itself.

The Tragic Hero: Boromir, who succumbs to a flaw in himself, but overpowers it in the end, before his death.

The Befated Hero: Aragorn, who was born to rise above evil and was given powers beyond those of lesser men to do this task.

The Reluctant Hero: Frodo, the true symbol of virtue and nobility, he undertook a task that seemed impossible and overcame the odds to succeed, where others had failed, even if he didn't want to do it.

Well that's my two cents.