Organization = Gundam Pilot
Age = 15
Ethnic origin = Japanese
Place of origin = L1 Colony
Eye color = Prussian Blue
Hair color = Dark Brown
Mecha Heero Yuy Piloted
Wing
Heavyarms
Wing Zero
Epyon
Leo Mobile Suit
Heero Yuy is the main character in the Gundam Wing series. He is the pilot of the title mecha Wing, and is known as pilot 01, probably because he was the first seen in the series. Although GW is a story about the impact of war on societies, that larger topic is told through the personal story of Heero and his experiences in that war.
We gradually learn as the series unfolds that Heero was not raised by his parents, but first by a professional assassin, Odin Lowe and then, after age 8 or so, by the brilliant but rather sinister figure of "Dr. J", the L1 Colony creator of Gundam Wing. Dr. J has apparently trained Heero from a very early age to be "the perfect soldier", and it's implied that his training regimen was harsh at the very least. Heero learned his lessons well. He has become as close as is humanly possible to the warrior that Dr. J envisioned; he has also, as a result, suffered a devastating loss of normal human emotional expression and relational skills. As strong a soldier as he is, Heero can't handle any form of close human interaction. When he is approached by others, he reacts by ignoring them or by threatening them.
Importantly, at the series halfway point, Heero is heard thinking to himself that he considers none of the other pilots to be his friends, but that two people have become extremely "annoying" to him. As the audience we recognize that this "annoyance" seems to come from the fact that Heero cannot ignore these people: he thinks about them a lot; he hears their voices and sees their faces during particularly stressful points in his life; he seems drawn to them somehow, even though he protests their desire to become part of his life: Relena Peacecraft, heiress to the Earth's Sank Kingdom, and Duo Maxwell, the pilot of Gundam Deathscythe, pilot 02.
Finally, as the lead character in Gundam Wing, Heero serves as a "standard" for the other characters in the series. When compared with the other pilots, Heero's physical abilities are supposedly superior, as are his skills in fighting, and his "devotion" to the cause they are fighting for. When compared with the "traditional" soldiers of the Federation and of OZ, Heero is almost always seen as smarter, more ruthless, and a true challenge to idea of what a soldier should be. And, unfortunately, when compared with almost all the other characters in the series, Heero's lack of emotion, his coldness, and his unstable mind stand out. Of all the victims of the war, Heero seems to have suffered the most shocking personal damage.