The Jjaro were a mysterious, extremely advanced alien species?/individual?, who disappeared from the Milky Way Galaxy millions of years ago.

Much of the Pfhor's technology derived from the Jjaro.[1]

References

  1. ^ Marathon 2: Durandal, For Carnage, Apply Within, Terminal 1, https://marathon.bungie.org/story/durandal2.html#M2.16.1.1