Archer
Archers were a mainstay in both the national and private armies of many Templars in both the Holy Land and Italy. They are typically some of the weakest soldiers in
Assassins Creed and are easily defeated with a single counter or with a stealth assassination. They detect Altair when he gets close, or when spotted in a restricted area and they fight with their bows at a distance and with standard longswords when the Assassin gets within range.
Assassin's Creed
Archers in Assassin's Creed appear on the rooftops of every city, and on top of large wooden structures in the Kingdom. They commonly have very low armor and can be killed with throwing knives; or approached for a stealth assassination. They are approximately as skilled as an ordinary soldier and will fall to a single counter attack.
Assassin's Creed: Bloodlines
Templar Archers are not as aware as the other archers in the other games and will usually only detect and attack you when you are being chased. They are significantly dormant and oblivious to Altaïr, except when he tries to climb a structure. Altaïr can now assassinate from ledges, making them the prime targets of this technique.
Assassin's Creed II
There are two types of archers in Assassins Creed II: regular longbow archers and fire-tipped longbow archers -- the latter attempt to make the carriage crash in the "Romagna Holiday" mission (they shoot the arrows which create circles of fire on the ground and force Ezio to maneuver around them) as well as shoot down the Flying Machine in the "Infrequent Flyer" mission and the "Battle for Forli" special memory.
Archers are always found on rooftops in all cities and carry longbows and medium weapons. They will shoot at Ezio on sight regardless of his Notoriety level and cause considerable damage to Ezio's armor. They will also hunt down Pickpockets or Borgia Messengers on rooftops if they pass by. If Ezio gets too close they will use their face-to-face weapons to hit him, but with very low armor and direct combat abilities, they make easy kills in close quarters. They can also be thrown from rooftops or ledge assassinated to be killed. In groups they can be lethal, as a small group could hold Ezio back, while the rest hits him with arrows.
There are special variations of archers found in Assassination missions and the Primary Memories. There are "Elite Archers" -- archers with the trademark Elite helmet and stats -- as well as "Captain Archers", which can be seen in the missions "Honourable Thief" (Venice Assassination mission) and in "Everything Must Go"(final Sequence 7 mission), although the archers in the latter mission are actually thieves and wear their trademark head wraps.
Assassin's Creed Brotherhood
In Assassin's Creed: Brotherhood, archers appear less frequently then in other games because many of the guards that are put to watch over from rooftops are arquebusiers, they are equipped with an arquebuise (rifle) instead of a bow. Following this, Ezio has the ability to assassinate muiltiple guards by ordering his apprentices to fire a flurry of arrows at them while he simply continues his route.
See also
1. Guards
2. Arquebusiers