During the mid-23rd century, an alien race of unknown origin traversed through known space, attacking selected targets to test their defenses to ascertain whether or not it was worth conquest. To achieve this, the species sent out scout fleets that located and attacked potential targets, such as the Gaim or Babylon 5. The survival of such fleets against potential targets is what decided whether or not they were worth the resources to conquest, making it necessary for the targets to destroy most, if not all of the fleet.
In 2262, this species attacked Babylon 5 after encountering the Gaim sometime before, the latter of which were able to warn Babylon 5 in advance of the scout fleets arrival. Ships belonging to this species destroyed long range probes sent out into hyperspace by Babylon 5. Afterward, an initial wave of ships traveled through the jumpgate and attacked Babylon 5 and the launched Starfuries were destroyed though combat. Later, the species arrived with their main fleet, attacking the station with cruisers and fighters which were able to damage B5's hull with a few hits. Breaching pods allowed soldiers wearing suits of armor that covered their entire bodies to penetrate and attack the station's lower levels. All invading ships were eventually destroyed. 
|Arnassian Caretakers Delgashi Divloda Enphili Faranian Fen Golian Hive Mind Bacteria Kaitay Kinbotal Kulan's race Kurlin Lorkan Lumati Merla Mind-altering aliens Mipasian Moradi N'Grath's Race Na'ka'leen Nimue Norsai Orion Ralgan Riar Scout fleet race Servitors Sh'lassen Shoggren Soom Soul Hunter Streib Tak'cha Tikar Tokati Tzillari Vindrizi Vinzini Visitors Wychad|
|Shadow Servant Races|
|Keeper Shadow Surgeons Sleeper Soldier of Darkness Wurt|
|Extinct and Nearly-Extinct Races|
|Belan's race Ceti Daltron Dureena's race Ikarran Original Lorkan Taratimude Varn's Race Xon|
|Alacan Cauralline Cthulhin Deneth Froon Krish Mitoc Morellian Thrantallil Throxtil T'llin Tuchanq Ylinn|