Arrows are fired by bows and crossbows and were used by many armies of Middle-earth, especially the elves, but also by the Men of Rohan, Gondor, Dale, and those of Mordor.
In Moria, an orc arrow bounced off Frodo's mithril chainmail, while another stuck through Gandalf's hat.
The Red Arrow was a way Gondor summoned its allies in time of need.
Bard the Bowman had a unique Black Arrow, which he claimed he always retrieved every time he fired it.
Arrows were the very weapons that ended vile enemies such as Smaug and the War of the Ring, and when the Hobbits of the Shire shot Gríma Wormtongue dead after he killed Saruman.
The army of Uruks from Isengard had crossbowmen as their archer unit, when they besieged Helm's Deep.