The Merciless is a Multiversal version of Batman from Earth -12 of the Dark Multiverse.
To end the "Final War" against Ares, Bruce Wayne donned the God of War's helmet to usurp his power and use it against him to stop the war. However, the helmet's corruption overpowered the Dark Knight's moral code, turning the hero into a warmongering behemoth known as "The Merciless".
When the Olympian God of War Ares created a helmet that amplified his powers a hundredfold, war broke out in the effort to stop him.
For two years, Batman and Wonder Woman fought side-by-side to get close enough to attempt to stop Ares and in the process succumbed to their love for each other. While the two were able to get the helmet off the war god, the effort led seemingly to Diana's death. Batman, driven by grief, put the helmet on to gain the power to kill Ares, believing that he could keep himself under control and use the power of war for good. However, Batman was corrupted by the power and renounced all sense of moral control or "mercy" in his battle to end the war. Afterwards, he learned that Diana had only been stunned by Ares. Afraid of what Ares power would do to Bruce, she tried to remove the helmet. However, Bruce was so addicted to the power, he chose to kill the woman he loved rather than risk losing the helmet. With virtually unlimited power and no sense of morality, Bruce went on to wage war on the entire world. Starting with killing only villains, he quickly escalated to killing his fellow heroes when they tried to pull him out of the darkness and then he proceeded to conquer the planet.
- The Merciless is the final boss in the Metal Pt. I: False Idols 8 player operation.
- The Merciless is one of the final bosses in the Metal Pt. I: Monsters of Metal 8 player operation.
- A mental image of The Merciless is one of the possible mini-bosses in Metal Pt. II: Batscape.
- The Merciless, along with other Dark Knights, is fought at the end of both Metal Pt. II: The Phoenix Cannon and Metal Pt. II: Into the Dark Multiverse.
- The Merciless first appeared in Dark Nights: Metal #2 (November, 2017).
- The Merciless wields the God Killer blade as his weapon of choice. A mystical, semi-sentient blade crafted by Hephaestus, God of the Forge, the God Killer can adjust its weight and shape and strengthens the user in the heat of harsh battle, guiding and partially controlling their actions.
- The Merciless possesses a giant golden drachma (ancient Greek currency), created from the coins of every amazon who was killed during his three-day campaign to conquer Themyscira. As the God of War, he had ordered the ferryman at the river Styx to collect the coins the amazons had given him while seeking passage into the afterlife, preventing them from gaining entry to the Elysium fields and making them his summonable army for as long as the drachma remains in his possession.
- Each member of the Dark Knights represents one of Batman's worst fears and regrets. The Merciless represents Batman's fear of who he would become if he started killing, how Wonder Woman helps him see the good in people and his regret that he really cannot end his crusade since his villains keep coming back.