Apocalymon

Apocalymon (sometimes Apokarimon) takes the form of a pale-skinned humanoid in blue spandex, a black cape with red trimming, a grey helmet with yellow markings, and a scar on his left eye. His arms are long with black bands on the forearms and his hands are larger than normal hands, and have red claws. His hair is a dirty white, and he has yellow eyes. From the waist down is a giant polyhedron the size of a planetoid (he does have legs and can, in fact, separate from the polyhedron body) that can bring out giant metal claws on DNA-shaped chains. Filled with dark thoughts, he was born from the assimilated data of every Digimon that failed to digivolve. His name is a play on the word Apocalypse, which in the Bible is the end of the world. Although he was sealed away, Millenniummon freed him.

It seems as though Apocalymon is among the most powerful Digimon in the digital world, as demonstrated when he copies other Digimons' attacks, easily destroys the DigiDestineds' Crests, and almost killing both the tamers and their digimon.

Digimon Adventure
In "Now Apocalymon", Apocalymon mentions that his polyhedron portion contains his heating and cooling systems, stating he is the "Ultimate evil, complete with hot and cold running water".

Digimon Tamers
Apocalymon was one of the many Digimon silhouettes surrounding Rika and begging to be her partner.

Digimon World 3
Appears as a digimon partner of two Mech Soldiers on Gunslinger. Initially, it attacks by using a tech called Darkness Chaos, and when it is weak, it uses a simple attack. It is also a black Mega Digimon card with 50/51.

Digimon World 4
Apokarimon is the boss of Apokarimon Space in Doom Dome.

Digimon Adventure: Anode/Cathode Tamer
Apocalymon is Kimeramon or Machinedramon's Variable, dealing a lot of damage.

Digimon Adventure 02: Tag Tamers
Apocalymon digivolves from a line 35 Myotismon.

Digimon Adventure 02: D-1 Tamer
Different Apocalymon are bosses.

Digimon Tamers: Brave Tamer
The Apocalymon card, titled "Ankoku" teaches a Digimon the Ankoku technique. Ankoku makes one random enemy's attack fail.

Digital Monster D-Project
Apocalymon digivolves from Arukenimon.

Digimon Digital Card Battle
Apokarimon belongs to Dark card group. Apokarimon's card is strongest and largest HP can reach, which about 2700. His crash cross attacks, releases massive damage. Apokarimon appears as the Battle Master of Infinity Tower. After his defeat, he will randomly appear in the various cities, and repeatedly defeating him will win the player the Apokarimon card.

Digimon World Dawn/Dusk
Apocalymon digivolves from Phantomon, but only if you have already obtained him. He can be DNA digivolved from either Piedmon and Machinedramon or Puppetmon and MetalSeadramon. In order for the DNA digivolution to be successful, the component Digimon must be at least level 70 with at least 44444 Dark experience points, and the player must have already acquired Piedmon. Apocalymon is also a level 90 member of Gaia Origin.

Attacks  Variation/Subspecies 
 * Darkness Zone: Reverts his enemies to a mass of data.
 * Total Annihilation (Grandis Big Bang): Suicide attack that produces an explosion strong enough to wipe out an entire dimension. Used as a final resort.
 * Reverse Digivolution (Death Evolution): Uses his giant claws to force Digimon to de-digivolve.
 * Virus Grenade: Launches laser grenades at his opponents.
 * Copy Attack: The giant claws morph into specific parts of other evil Digimon and enable Apocalymon to use the attacks of other evil Digimon. He used MetalSeadramon, Myotismon and Machinedramon's attacks to express his inner feelings towards the DigiDestined, while using Devimon's attack to snatch the Digidestined's crests and destroy them.
 * MetalSeadramon's River of Power (MetalSeadramon's Ultimate Stream): His giant claw turns into MetalSeadramon's head to launch a giant laser blast from its nose cannon.
 * Myotismon's Crimson Lightning (Vamdemon's Bloody Stream): His giant claw turns into Myotismon's torso to create a red energy stream that it can throw out like a whip.
 * Machinedramon's Giga Cannon (Mugendramon's Mugen Cannon): His giant claw turns into Machinedramon's torso to release energy blasts from its cannons.
 * Devimon's Death Claw: His giant claw sprouts Devimon arms to grab things. Apocalymon retains the Japanese name of the technique.
 * Apokarimon (Creepy Mode)