Negamon is the main antagonist of Digimon Adventure:, the 2020 reboot series of Digimon Adventure.
Working from behind the scenes, it works to bring various cataclysms to the Digital World to help it evolve from accumulating and learning over the course of the Digital World's existence.
However, Negamon's most recent attempt at creating a disaster results in it getting corrupted by the negative energy that it absorbs and developing an insatiable hunger to consume both worlds. After Negamon is destroyed by Omnimon Alter-S, it reformats into a Digi-Egg, hopefully to be reborn into a better existence not bound to either good or evil.
It was voiced by Takashi Matsuyama who also voiced Argomon in the Japanese Version.
Throughout the Digital World's history, Negamon would bring various disasters to cause the Digital World to evolve and grow through the accumulation of data and learning. One such disaster that Negamon would cause is Ghoulmon's ancient war with the Army of Light which ends when Omnimon destroys ZeedMillenniummon.
In August 2020, Negamon begins its plans for a new disaster by dropping a swarm of Digi-Eggs into the Network which hatch into Argomon. However, Argomon's attempt to destroy Tokyo with a nuclear missile is foiled by Omnimon who destroys Argomon and redirects the missile into outer space. Undaunted, Negamon releases another Digi-Egg into the Network which hatches into Eyesmmon which begins collecting data for Negamon. However, after Eyesmon digivolves into Nidhoggmon, it is destroyed by Omnimon. Negamon finishes the countdown itself and sends all but Taichi, Yamato and their partners through a portal back to the Real World.
As the Chosen Ones contend with Millenniummon's followers, Negamon continues to plot and work from behind the scenes, having its followers continue to cause various disasters in order to create chaotic data and energy for Negamon to feed on. However, this has the unexpected side effect of corrupting Negamon and its initial purpose, instead giving Negamon the insatiable hunger to consume all existences into a white void, an event known as the Great Catastrophe.
Following Millienniummon's final destruction, Negamon becomes more active as it begins preparing for the Great Catastrophe. Upon learning that the Chosen Ones are at the Great Tree of Information, it has its Soundbirdmon minions brainwash a Burpmon in order to consume the data related to the Great Catastrophe. Although Burpmon is successfully destroyed, the data is scattered in the process and needs to be recollected as a result. Negamon later sends a swarm of Argomon to test Taichi and Agumon's bond with the Ultimate-level leader issuing a warning that its master will soon begin the Great Catastrophe before retreating.
After the Chosen Ones unlock the true power of their Crests, Negamon sends a legion of Soundbirdmon to attack the Tree with Devimon sensing that the Great Catastrophe is about to begin and warning Takeru and Patamon of the approaching threat. Many of the Soundbirdmon fuse into Ghoulmon, but it is destroyed by Seraphimon and Ophanimon, destroying all of the Soundbirdmon along with it. As Ghoulmon dies, it warns that it is merely "the first cry of the catastrophe" which will begin when its cry ends. As Ghoulmon dies, Negamon's orb light up and it begins sucking the Digital World into its white void, beginning the Great Catastrophe.
Negamon sucks the Chosen Ones into its void, leaving their partners behind, but the children are protected from deletion by their Digivices. The Ultimate Argomon, transition to its Worm Phase and then eventually digivolving to Mega, confronts the Chosen Ones and reveals Negamon's history, purpose and current intention to consume both worlds into its void. With the help of their allies, the Digimon manage to get into the void and destroy the Argomon, digivolving all the way to Mega to take care of the Mega Argomon. However, as the Mega Argomon dies, Negamon begins consuming the Real World too.
As the Chosen Ones turn their attention to it, Negamon digivolves into its Giant form. WarGreymon, MetalGarurumon, Seraphimon and Ophanimon enter Negamon's orb to confront it while the other Digimon begin destroying the tentacles sucking data up. After a brief fight, Negamon (Giant) is apparently destroyed by WarGreymon and MetalGarurumon, but Hikari realizes that they only destroyed its shell just as Negamon's true form merges with its black orb to digivolve into its Mega form of Abbadomon.
Abbadomon resumes absorbing the two worlds and turns most of the Chosen Ones and their partners into ghostly forms with only Taichi, Yamato, Takeru, Hikari, WarGreymon, MetalGarurumon, Seraphimon and Ophanimon left to face it. The four Mega Digimon prove to be no match for Abbadomon who strikes down WarGreymon and MetalGarurumon and swallows Seraphimon and Ophanimon into one of its tentacles.
Just as all seems to be lost, humans from across the Real World send their hopes to the Chosen Ones, restoring them and their Digimon with the positive energy while shades of Devimon and SkullKnightmon appear to rescue Seraphimon and Ophanimon. The Mega Digimon send the power to WarGreymon and MetalGarurumon who DNA Digivole into Omnimon. While the others remain outside, Omnimon breaks into Abbadomon's orb, ready to end it and the Great Catastrophe once and for all.
In the heart of the orb, Omnimon encounters Abbadomon Core, Abbadomon's core body. While the others continue to fight with Abbadomon's orb, Omnimon battles Abbadomon Core who proves to be a match for the Royal Knight, nearly destroying him. However, the children's determination to keep fighting gives Omnimon the power to Mode Change into Omnimon Alter-S who effortlessly beats back Abbadomon Core before slicing it in half with his sword. Abbadomon Core's upper half turns into a giant purple cloud with a fanged mouth that swallows Alter-S, only to have Alter-S blow this form up from the inside before reverting into Omnimon.
With its core destroyed, Abbadomon's orb begins shrinking down, stating that it will vanish as the Great Catastrophe ends. However, Omnimon points out that as a fellow Digimon, Abbadomon should be reborn into a new life which Omnimon expresses hope will be bound to neither good nor evil, but will give it a choice for a new better existence instead. Abbadomon reformats into a Digi-Egg that vanishes in a streak of white light. Watching this, Omnimon bids farewell to Negamon and promises that they will meet again in the future. Omnimon then destroys Negamon's area in the Network before the Chosen One's Digivices restores all of the data that Negamon had absorbed into its void, reversing the damage that it had caused.
- At the end of the series, a Digi-Egg is shown to be hatching. It is unclear if this is meant to be Negamon being reborn or just another Digimon hatching from their Digi-Egg.
- Its Japanese voice actor, Takashi Matsuyama, who also voiced Mushamon in Digimon Adventure 02, and Snimon in Digimon Frontier.