James Rhodes, Iron Man's friend and ally.
The War Machine armor is a heavier more offensive oriented version of the Iron Man armor. This armor is normally used by Tony Starks friend James Rhodey Rhodes.
Rhodes appeared in the first Iron Man film helping Tony get out of a situation with the Air Force attacking him. He also helped in the search for Tony while he was captured by the Ten Rings. The War Machine armor did not make an appearance but was strongly hinted at when Rhodey looked at a prototype armor saying "Maybe Next Time"
In Iron Man 2 both Rhodey and War Machine make an appearance. The relationship between Rhodey and Tony is strained as Stark continues to be reckless with his brand of vigilante justice. Rhodey is torn between his friendship to Tony and his duty as a military man. Rhodey eventually puts on a prototype Iron Man suit to take Tony out when he gets drunk and reckless at his own party. The ensuing battle ends when Rhodey leaves with the prototype armor and turns it over to the military. From there the army turns to Tony Starks rival Justin Hammer to modify and weaponize the suit for someone to wear. Rhodey is chosen to wear this new War Machine armor and it is shown off along with the Iron Drones at the Stark Expo. After regaining control of the suit Rhodey assist Iron Man in taking out both the Drones and a returning Whiplash.
The War Machine Armor also makes an appearance in the Marvel animated film Ultimate Avengers 2 only this time it is warn by Tony Stark.
War Machine has also appeared in both the Iron Man cartoon and Spiderman cartoons with it being warn by Rhodes.
James Rhodes defining trait is his intense patriotism and sense of duty. He is profoundly loyal to his country (the United States) and will do anything to defend it. James Rhodes is a good soldier who cares deeply about his work.
In the comics, it is revealed he was a troubled and aggressive teenager who spend months in juvenile prison for fighting neighborhood boys over what he felt was right. This past has not yet been touched upon in films or television, but his deep sense of right and wrong is always apparent.
Unlike most super-heroes in the Marvel universe, War Machine is very confidant with killing his foes. He does so far more frequently than most of his team-mates and never regrets it.
James Rhodes is of average height, is black, and is probably in his forties.