Peddlers are Imperial traders that can be found in a random encounter while wandering Skyrim. They are usually found mounted on a horse, and even if they die in combat, the horse is still marked as "stolen." They are mostly encountered in the Reach, although they can also be found in other parts of Skyrim.
The Dragonborn can sometimes encounter a peddler in the Reach, being attacked by the Forsworn or bandits. If they receive help, they will thank and offer selling their wares to the Dragonborn. They often sell random, useless goods, but sometimes they may have alchemical ingredients or low-level weapons.