The YuuYan Archers
Numbering in nearly a dozen, the YuuYan Archers are legendary for their precision and skill. So great are they, that they can pin a fly to a tree 100 yards away, without killing it. For a while they served under the command of Colonel Shinu, who used them as security guards at his Fire Nation fortress in the northern area of the Earth Kingdom.
In the middle of Book 1, Commander Zhao requested that he use their skill to capture the Avatar, but he was denied. When he was promoted to Admiral, though, his request became an order and the YuuYan Archers were under Zhao's control. They even succeeded in capturing the Avatar, although he soon after escaped thanks to outside help.
The YuuYan Archers still seem to be aiding the Fire Nation in their world conquest and capture of the Avatar. One of the Archers was seen in the southern Earth Kingdom in episode 5 of Book 2: Earth.
The YuuYan Archers are recognizable by the red war paint on their faces -- a thick bar that widens like an ax around their eyes, and then two small diamonds, one above and below the bridge of their nose. In addition to their matching uniforms, they also wear headbands with a red triangle on it. The same marking also appears on the back of their box-like quiver.
On both hands their thumb, index and middle fingers are covered with a special glove that protects their fingers from the friction of shooting their bow.
Besides their individual skills, another reason why these archers are so formidable is because they work together so well. They attack as one in multiple waves, barely giving their prey a chance to breathe or think of a proper counter-attack. They are swift, agile, and think quickly on their feet. Coupled with their dead-on accuracy, they are quite the imposing force.