Prototype Digimon (プロトタイプデジモン, Purototaipu Dejimon) refers to experimental Digimon that served as the basis for the creation of new Digimon or for other specific experiments. The Prototype Digimon that exist from before Digimon were discovered have an outdated Interface on their brow that allows for reconfiguration of the data stored within their Digicores for such experiments.
At the Genesis of the Digital World, Yggdrasill conducted a stand-alone experiment to create "the strongest Digimon". Two series of experimental Digimon were created for this experiment, to achieve the definition of "strongest" from different perspectives.
The "DORU Series" (ドルシリーズ, Doru Shirīzu), a portmanteau of "Digimon OR Unknown-Monsters", is a term which refers to a series of Digimon created to achieve the definition of "strongest" through further evolutions.
During the experiment, the potent life-force data of the legendary beast, the "Dragon", was hidden within the deepest parts of their Digicores, giving them the potential to grow into mighty Digimon. The "DORU" in DORUmon's name seems to be a remnant of this term.
Furthermore, because of the experiments many of the prototypes died and were horribly modified by using the old relic data Death-X, and the Digimon of the "DORU Series" can force the X-Antibody within their Digicores to allow them to remain functioning even after they have died, evolving through an special type of evolution known as "Death-X-Evolution", whose mysteries are known to Grand Dracumon. Despite their deceased condition, they can remain active by preying on the Digicores of other Digimon. It's said this was done to allow the DORU Series to achieve "infinite vitality".
|ドルシリーズ Doru Shirīzu|
The Ryu Series (リュウシリーズ Ryu Shirīzu) is a term which refers to a series of Digimon created to achieve the definition of "strongest" by pursuing further fighting strength 
During the experiment the ferocious combat data of the "Dragons" and "Generals" of Japanese mythology was hidden within the deepest parts of its Digicore, giving it the potential to grow into mighty Digimon. Its evolutionary body is called the "Ouryumon species". 
Furthermore, the Ryu Series' rate of improvement of muscle strength parameters that increase in battle and the ability to make decisions in battle were artificially enhanced. It seems to be a tentative to create the "strongest" Digimon that no other Digimon could match in battle.
|リュウシリーズ Ryu Shirīzu|
Andromon and Boltmon were developed at the same time by a group of scientists as the prototypes for Cyborg Digimon. Andromon was made emotionless and mechanically-based, while Boltmon was organically-based and as such possessed emotions and power that surpassed Andromon's. Their technology was later successfully adapted into other Cyborg Digimon such as Metal Greymon and Megadramon.
|Metal Greymon (Virus)|
- Arkadimon Baby was one of the experiments to create the "Ultimate Digimon"
- It is uncertain if Chimairamon was built as a prototype for Mugendramon or to be used against it.
- Plotmon was created as an experimental Digimon to imitate the pets that live with humans, and because of that has an appearance close to that of a real animal.
- Snimon was created as an experimental Virus Hunter Digimon, designed to track down targets as if it were a precise machine.
- Rinkmon was created when an experimental Digimon, the "Digimental of Friendship", and the sample data of an experiment that accelerated elementary particles to the speed of light with an accelerator, were fused.
- It is said that N.E.O, a mysterious digital lifeform, is the basis (Adam) for "Next-generation Digimon" sent by the system that governs the Digital World, although this is just an hypothesis.
- Loogamon is presumed to be an experimental "Prototype Digimon" from before Digimon were discovered because of the outdated Interface on its brow.
- Because it has an outdated Interface on its brow, Loogarmon is presumed to be an evolution of a "Prototype Digimon".