The Doppelgangers are villains from DragonFable and AdventureQuest Worlds who usually act as copies of The Protagonist.
Kathool Atchoo's Doppelganger
This Doppelganger was first created by Kathool Atchoo as a mental obstruction to the Hero, and was anthromorphised as a dark shadow, also has the power to copy the Hero's abilities and name exactly, almost like an doppelganger. The Doppelganger first appeared in The Locker as the Doppelganger taunted the Hero and cast doubts about how to protect Aquella, and moreso how the Hero's true strengths also elaborates the Hero's mental weakness in their own nightmares.
As the Hero begins talking to the Doppelganger in the Locker, it makes the two other people who are also watching the Hero (the Death Knights) think that the Hero is both hallucinating and crazy. In its natural form, the Doppelganger looks more like a flickering black flame with glowing purple eyes but only The Hero can see this menace.
As the mental battle unfolds, the Doppelganger mimicks the Hero's own battle moves exactly and the Hero will have to battle the Doppelganger six times before the mental being finally fades away as the Doppelganger was defeated.
13th Chaos Lord Doppelganger
This Doppelganger acts as the Hero's Chaos Lord copy and will have the same clothing and weapon as the Hero but is slightly taller than the original and acts as the final opponent before the final battle with Drakath and eventually gets defeated by the Hero.