The Shadowen are creatures of magic. They were originally Elves who uncovered knowledge of the earth magic from the Age of Faerie and were subverted by it, but later began including members of the other Races.
Shadowen feed upon magic drawn from the earth, which causes the land to sicken and die as it loses the magic. They cannot be killed by normal means, as they have the ability to heal quickly and even reattach body parts that have been cut off. They must be killed by some form of magic.
The Shadowen are not like the Demons from the Age of Faerie that were trapped in the Forbidding. Instead, they resemble the Demons of the Word/Void series in that they are regular people who have intentionally corrupted themselves with evil magic, and in that they can shed their bodies in order to inhabit new ones.
Southwatch was a massive, magically created black tower and living organism that served as the headquarters and a feeding ground for the Shadowen. Southwatch stood near Rainbow Lake and was used by the Shadowen to trap and siphon off the earth magic they fed on in large quantities. Southwatch also served as a prison, as was the case for Coll Ohmsford. Like the rest of the Shadowen's creations, Southwatch was destroyed when Par Ohmsford released the trapped earth magic.
The artificial creatures on the island of Morrowindl which were corrupted and became evil were called Demons by the Elves, after those trapped in the Forbidding. However, they were in fact different varieties of Shadowen. Types of Shadowen included the Drakuls and the Revenants, as well as unique creatures like the Wisteron. All of the island's Shadowen were destroyed by the eruption of the volcano called Killeshan.
- Famine/Pestilence/War/Death — These Shadowen, modeled after tales of the Four Horsemen of the Apocalypse, each rode a dangerous, giant lizard instead of a horse. Of the Shadowen sent to kill the Scions of Shannara, they were the most deadly. They were sent to battle Walker Boh at Paranor, and he managed to defeat the first three on his own, by turning their powers on each other. He only was able to kill Death with Cogline's assistance, and Cogline perished in the battle.
- Hirehone/Teel — Hirehone, a blacksmith working for the Free-born, was possessed by a Shadowen, giving it access to the Free-born's secrets. This Shadowen later possessed Teel, a Dwarf who had penetrated the Free-born headquarters at the Jut in Parma Key. Despite the Shadowen's best efforts, the Free-born escaped and it was killed by Morgan Leah.
- Rimmer Dall — Some Shadowen, in particular those who can easily pass as normal people, masquerade as Seekers, the magic-hunting police force of the Federation. Rimmer Dall is the First Seeker during the rise of the Shadowen. He coveted Par Ohmsford's body because Par had the use of the wishsong, and he played a complicated mind game with Par to try and get Par to succumb to him. However, Par ultimately managed to resist and eventually defeat Rimmer Dall.
- Tib Arne/Gloon — Two Shadowen, one disguised as a boy and the other as a War Shrike. They were tasked by Rimmer Dall with capturing Wren Elessedil. They gained Wren's trust and eventually betrayed her and took her hostage. The pair were later destroyed by Wren, the Wing Rider Tiger Ty, and his Roc Spirit.
- Wisteron — One of the most feared Demons on Morrowindl, described as a giant cross between a spider and a monkey. The creature lived in the In Ju swamp, setting webs and traps to catch its victims. Although Wren and Garth had managed to avoid the creature when traveling to Arborlon, they were forced to go to the Wisteron's lair while taking Arborlon off the island because Gavilan Elessedil was caught by the Shadowen after stealing the Loden and the Ruhk Staff from Wren. The Wisteron was so powerful that Wren's Elfstones could not destroy it. Wren resorted to concentrating the power of the Elfstones on the mud beneath the monster, causing it to liquefy and the Wisteron to sink and drown. Garth was poisoned by the Wisteron's venom. When he realized the poison was turning him into a Shadowen, he convinced Wren to kill him to avoid being transformed.