The Serpent Riders are a trio of sibling demons, bent on domination of the known universe. They are the central, but separate main enemies of Heretic, Hexen and Hexen II. The symbol of the three appears similar to a Neptune trident, although it is featured prominently only in Heretic. According to the Chronicle of Deeds (a fictitious work written by Themedes of Mur from Septimus on the world of Thyrion), as detailed in the manual for Hexen II, the Serpent Riders were able to enter the mortal universe from the chaos outside when the captain of a star-faring magical vessel accidentally pierced a crystal dome at the edge of reality with the bow of his ship. Though the celestial sailor sacrificed himself in order to seal this breach, three of the innumerable demons on the other side—the Serpent Riders—were able to make it through before he could complete his work. They then went about sowing seeds of chaos throughout many different dimensions.
The three Serpent Riders are as follows:
- D'Sparil - Appears in Heretic. Boss of Episode 3: The Dome of D'Sparil. Youngest and assumed the weakest of the three, he has 3500 hit points, and rides a special Green Chaos Serpent with 2000 hit points. He holds a mix of offensive and defensive abilities, one of which includes teleportation.
- Korax - Appears in Hexen, at the end of the Necropolis hub. Is the middle age, and assumed to be the middle strongest rider. He has 5000 hit points, but is deemed an easier opponent than the Heresiarch due to his slow movement. He can control various devices and traps in his chambers, teleport in monsters, or teleport himself around at will.
- Eidolon - Appears in Hexen II, at the end of the Return to Blackmarsh section. He starts off with 4000-8000 hit points, depending on the difficulty, and appears to be small. He is actually the strongest and oldest rider, and once the Chaos Sphere appears, he proves this point definitively. He grows to a larger form in which he has between 6000-14000 hit points, and the Sphere must additionally be destroyed now to harm him. He is an all attacking boss, and does not spawn in other enemies or teleport around to get the upper hand, and fights with magic and brute force. His appearance also vaguely resembles the baron of Hell.
D'Sparil upon his chaos serpent mount, within his fortress beneath the seas of Parthoris.
- Chaos Sphere - The artifact used for extra power by the Serpent Riders.