Mobius

"Universe after universe has fallen before my power. World after world consumed. With every death, I steal my mirror’s strength and mine grows ever stronger. Who am I? I am the Anti-Monitor. Come, Harbinger. There is work to be done."

- Anti-Monitor

Mobius, better known as the Anti-Monitor, is a being of supreme power and malevolence that succeeded in his mission to eradicate the multiverse by whatever means necessary. He was opposed by his counterpart, Mar Novu, also known as The Monitor.

Biography
At some point, Mar Novu allowed for Mobius to live, a decision the former would come to immensely regret.

Imprisoned
Seeking to destroy the multiverse with waves of antimatter, the Anti-Monitor was sealed behind a door in a chamber where he built an anti-matter cannon to execute his scheme. When Barry Allen of Earth-90 charged towards Novu and was repelled, he found himself within the reach of the Anti-Monitor, who whisked him into his prison and forced him to run on a treadmill to power the weapon. During a test run of the antimatter cannon, the entire universe of Earth-2 was eradicated.

Messaging Nash Wells
On December 9, Harrison Nash Wells, mistaking Mobius for Mar Novu, stood outside Mobius's door and taunted him, saying how he didn't believe in false gods. Mobius argued with Nash to no end, when suddenly Nash was attacked by one of Ramsey Rosso's blood brothers. After a while, Ramsey and his army were stopped thanks to Allegra Garcia, but Nash believed it was "the Monitor" who saved him. At 11:58 pm, just as Nash was about to open the portal to what he believed would be the Monitor's realm, Mobius noted on how he wished to know the truth and offered to reveal to him what he wanted to know in exchange for his service. Mobius told him to stop his attempts to kill him and begin a new life. When Nash asked Mobius to show him, he said that he already has "the knowledge" (probably to solve a code). After Nash solved the code in the cave, Mobius opened the rock and pulled him inside it in a flash of light before slamming down the rock wall again.

Released
Due to Nash openning the door, Mobius was released and the Crisis was begun. The Anti-Monitor began consuming inumerous universes across the multiverses.

Corrupting Harbinger
Due to more worlds being destroyed, the Anti-Monitor soon communicated with Harbinger through unknown means and, despite her pleas to stop, forcibly summoned her to his lair. Once she arrived, Mobius introduced himself. After revealing that worlds were falling under his power and every death allowed for him to steal more power from his mirror counterpart, Mobius demanded Harbinger's cooperation and proclaimed that there was work to be done.

His Successful Endgame
He possessed Harbinger and after all except Earth-1 was destroyed and all the multiverse's refugees were brought to last remaining Universe, he teleported to the Waverider and tried to fool the multiverse's heroes. However, they saw through his guise and futility tried to kill him. He over-powered the heroes and had his Antimatter wave destroy Earth-1 and the Mmultiverse's survivors as well as murder Mar Novu as the heroes helplessly watch. As the wave was heading towards the ship, Pariah teleported the multiverse's last line of defense to a place where Mobius could never find them. Before they died, the heroes with their last breath warned Mobius that this isn't over and those that Pariah saved will "fight to their last breath" just before the Antimatter wave destroyed them, completing Mobius' victory.

Personality
The Anti-Monitor had proven to be an incredibly evil being, wanting to destroy the entire multiverse, killing off an infinite amount of innocent lives without any guilt or remorse. He seems to enjoy taking credit for destroying universes and consuming worlds. He is also extremely intelligent and manipulative, able to convince the extremely intelligent Harrison Nash Wells into freeing him. Ultimately, his intellect prevailed as he succeeded in his mission.

Powers

 * Cosmic entity physiology: The Anti-Monitor is stated to be far more powerful than Mar Novu himself, a remarkably powerful cosmic entity in his own right and is most likely one of the most, if not the most powerful being in the entire multiverse.
 * : When inside his prison, the Anti-Monitor was able to communicate with Harrison Nash Wells when he was standing in the rocky wall that held the portal to his prison.
 * : The Anti-Monitor was able to effortlessly pull Harrison Nash Wells inside the portal to his realm without even being physically present.
 * : Through Harbinger, he was able to project energy blasts to fight against Mar Novu.
 * Antimatter Projection: The Anti-Monitor induces anti-matter wave that destroys Earth-1 even the Antimatter Cannon is destroyed.
 * Essence absorption: The Anti-Monitor has the ability to absorb the essence of his counterpart, Mar Novu, killing him in the process.
 * Possession: The Anti-Monitor took possession of Harbinger and used her body to kill Mar Novu and absorb his essence into her body.
 * Extended longevity: The Anti-Monitor has lived since the dawn of time.

Abilities

 * Genius-level intellect/Master strategist/Master of deception and manipulation: The Anti-Monitor has been shown to be skilled at manipulation. Being able to convince Harrison Nash Wells to free him.
 * Intimidation:

Weaknesses

 * Paragons: Mar Novu predicts the seven paragons are the only people who can take the Anti-Monitor down.

Equipment

 * Antimatter Cannon: It was the ultimate weapon of mass destruction that produced the antimatter waves that Mobius used in order to completely destroy the multiverse. This was later destroyed with the help of Team Flash, the Flash of Earth-90, Black Lightning, and Pariah.

Trivia

 * The Anti-Monitor's endgame was foreshadowed by Zoom's final scheme, seeking the destruction of the multiverse using a machine powered by speedsters running on it.
 * Though unlike Zoom, he didn't want to leave a single universe to survive, but rather rule the remaining antimatter universe alone.
 * Also unlike Zoom, he succeeded.

Behind the scenes

 * The Anti-Monitor is the most dangerous villain in the shared multiverse as he is with the largest body count. Except for the Paragons, he has murdered an infinite amount of people by destroying the multiverse with antimatter.
 * His physical appearance has been pointed out by fans to resemble Marvel villains like Apocalypse and Thanos. Some have even noted that his facial appearance looks like a White Walker or their leader, the Night King, from the Game of Thrones HBO television show.