D-Reaper

Exclusive to the Digimon Tamers series, the D-Reaper was a nigh-unstoppable force existing only to destroy anything that went beyond its boundaries.

Mother D-Reaper (49-51)
Using Jeri's negative energy, the D-Reaper of the Real World underwent an advance evolution, reabsorbing its agents and becoming the Mother D-Reaper. It managed to create more powerful versions of its most deadly agents and swallowed all of Shinjuku. The Tamers managed to get in (via the Red Card) and save Jeri before the Mother D-Reaper fell victim to Operation Doodlebug. It got sucked into (Shaggai)/Juggernaut and regressed back into a harmless program.

Cable Reaper (50-51)
The D-Reaper of the Digital World surpassed its own boundaries and was to assimilate with Mother D-Reaper to complete the plan. But it was dragged back into the Digital World by the Sovereigns, allowing Operation Doodlebug to begin.

Agents

 * Jeri-Type: (40-51) This Agent was created for the purpose of espionage, posing as Jeri while the real one was in the Kernel Sphere. The Jeri-type was one of a kind and the only Agent not to need a cord to be linked to the D-Reaper. She eventually revealed her true form to Takato after manipulating the boy's feelings with her Mind Scan. She was eventually reabsorbed back into the D-Reaper with her face as Mother D-Reaper's first defense and the more stronger faceless version of herself as the last defense. She was finally killed by Gallantmon Crimson Mode.


 * Searcher: (42-43, 45, 47) Created for information gathering, these small bird-like agents appear in large numbers. They are the only type of Agent not made for fighting. Once, the Tamers got scared of a swarm of these but Guilmon wasn't scared and was even winning a staring contest with it until Takato dragged him off.


 * Pendulum Feet: (42-43, 45) The first Agent of the D-Reaper the Tamers fought. It has the ability to mimick a Digimon's attacks. Built for aerial combat, it had a long distance floating attack. After it was killed by Beelzemon Blast Mode, more were created for future fights.


 * Bubbles: (44-50) Built for ground assaults, these Agents have pulse cannons in their arms and move in groups.


 * Creep Hands: (44-45, 50) This medium sized Agent was adapted for hand-to-hand combat. Its arms were extentable.


 * Horn Striker: (46, 51) This Agent was an overwhelming opponent; it took the entire team to kill it. They was mass-produced to serve as the second defense of D-Reaper but were easily destroyed by Gallantmon Crimson Mode.


 * Parasite Head: (47, 50) This multi-mouthed Agent was built not only for recon but for battle as well. Its attack patterns were unpredictable.


 * Optimizer: (47, 50) This giant Agent was a mother-ship and carried Bubbles in its body. It was destroyed by Gallantmon when he obtained Grani.


 * D-Reaper Ball/Gate Keeper: (48-49) This Agent was formed around the Kernel Sphere to protect it. It was assimilated back into the D-Reaper, forming the face of Mother D-Reaper in Episode 49.

Digimon Tamers
The program was created in 1970, as "the reaper" program created by the American Department of Defence to delete excess data and manage the growth of artificial intelligence. The reaper’s first job was to delete the Morris worm virus. In the 80s, Reaper was used as a basis for the top-secret security system of "Project Echelon". In 1990, the Reaper attacked the fledgling Digital World, which had recently become populated by the Digimon. The Reaper went on to follow its program by deleting Digimon and absorbing their data and soon underwent an evolution of its own. It buried itself away beneath the Digital World and slumbered as it transformed into a sentient being.

By the time of the Tamers series, the newly created D-Reaper began to stir from the sheer amount of excess data that had been caused by Digivolving and the growth of the Digital World during its period of inactivity. It took Jeri to learn more about humans, creating its first Agent. The main part of D-Reaper followed the Tamers to the Real World through the Hypnos system and immediately began to spread over Shinjuku, keeping the Kernel Sphere high between the two towers of the Hypnos building, with Jeri sealed inside as its source of energy due to her grief. Only the BioMerged Digimon were able to fight it until it evolved into the Mother D-Reaper. But through the combined effort of everyone in Operation Doodlebug, the D-Reaper was regressed back into its original, harmless state.