The Holowan Massacre or Holowan Disaster took place sometime before 15 BBY on the planet of Halowan. It involved the death of dozens of scientists and guards at the Holowan Laboratories at the hands of the assassin droid, IG-88. When he was activated, he executed his creators, programmed and activated his counterparts, and together with IG-72, he went through the facility, killing all the personnel. Once all of the employees they could detect were dead, they escaped the planet, and headed for Mechis III, beginning their plans for the galaxy.
- Therefore I Am: The Tale of IG-88
- (First appearance)
- Galaxy Guide 10: Bounty Hunters
- Cynabar's Fantastic Technology: Droids (As "IG Massacre")
- Star Wars: The Action Figure Archive
- The Official Star Wars Fact File 4 (ASS1–2, IG-88 Assassin Droid)