Sam Winchester (Atomic Monsters)

Sam Winchester was a former hunter had become the leader of a demon army after getting addicted to drinking demon blood.

Background
At some point, Sam gave into his demon blood addiction and became the leader of a demon army. When their friends Jody Mills and Bobby Singer tried to stop him, Sam killed them.

In response, Dean led an attack by hunters, including Benny, on the Men of Letters bunker where Dean killed several demons with angel-killing bullets. However, most of the other hunters were killed by Sam and his demons. After speaking with a dying Benny, Dean was confronted by Sam who refused to be stopped. Dean insisted that it was the demon blood and Sam had to fight it, but Sam refused and killed an approaching hunter. Dean pleaded with Sam to stop but Sam, his eyes turning black, snapped Dean's neck with telekinesis, killing him.

Season 15
In Back and to the Future, Castiel got a brief flash of this Sam killing his Dean when he tried to heal Sam's wound from the Equalizer.

In Atomic Monsters, Sam experiences a nightmare where he witnesses the alternate Dean's confrontation with Sam and his death.

In The Trap, God reveals that Sam has been seeing his memories of alternate Sam's and Dean's and their fates.

Powers and Abilities
Due to drinking demon blood, Sam is able to use his powers as one of the Special Children to great effect.
 * Telekinesis - With simple head motions, Sam is able to snap peoples' necks. This can sometimes cause his eyes to turn a demonic black.

Appearances

 * Season 15
 * Back and to the Future
 * Atomic Monsters