A hacker (ハッカー, Hakkā) is someone with the ability to force an item, program, or system to deviate from its intended programming to satisfy their own desires.
A malicious hacker once managed to disrupt the Computer Network, and it was still being repaired when Coelamon was discovered, while the evil feelings of hackers who abuse the Network produced Devidramon. Octmon was discovered from the virus that a fiendish hacker used to crash a rival's research computer. Although the Firewall prevents illegal entries from hackers, the very defenders of the Network are subject to being taken advantage of themselves as was the case with Guardromon, who was originally a Digimon that worked alongside Giromon in repelling those who try to illegally enter the Network until a malicious hacker infected it with a computer virus and was subsequently used by that hacker as means of protection from the Virus Busters. Tekkamon is said to have been created by an evil hacker to destroy programs in response to Giromon.
Digital Monster Ver. S: Digimon Tamers
Digimon World: Digital Card Battle
Digimon World 3
Digimon Story: Cyber Sleuth
Digimon Universe Appli Monsters
Katsura Rei is a black-hat hacker.
Digimon Universe Appli Monsters (Manga)
Digimon Story: Cyber Sleuth Hacker's Memory
Digimon and Appmon with hacking abilities