The Legion of Doom was a hacker

Hacker (computer security)

In computer security and everyday language, a hacker is someone who breaks into computers and computer networks. Hackers may be motivated by a multitude of reasons, including profit, protest, or because of the challenge...

 group active from the 1980s to the late 1990s and early 2000. Their name appears to be a reference to the antagonists of Challenge of the Superfriends. LOD was founded by the hacker Lex Luthor (Vincent Louis Gelormine), after a rift with his previous group the Knights of Shadow.

At different points in the group's history, LOD was split into LOD and LOD/LOH (Legion of Doom/Legion of Hackers) for the members that were more skilled at hacking than pure phreaking

Phreaking

Phreaking is a slang term coined to describe the activity of a culture of people who study, experiment with, or explore telecommunication systems, such as equipment and systems connected to public telephone networks. As telephone networks have become computerized, phreaking has become closely...

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