Zaglis was the Supreme Leader of the Neo-Fundamentalist Phlangites, a group operating on the astronomical object Zaraksander in the Expansion Region. Sometime between 0 ABY and 4 ABY, the bounty hunter Valken Gresh apprehended Zaglis, while simultaneously escaping the Neo-Fundamentalist Phlangite forces in the Fioer desert of Zaraksander.
As a result of this experience, Gresh vowed to avoid future confrontations with Zaglis and his followers, the bounty hunter stating that such engagements were not sufficiently lucrative. However, the very next day, Gresh found himself compelled to return to the Fioer desert and once again confront the Neo-Fundamentalist Phlangites. This was due to his having been hired to rescue the kidnapped daughter of Darred Eloinie, the Chief Executive Officer of Eloinie Petro-Munitions. Gresh later recounted his encounters with Zaglis and his adherents in his autobiographical work, Great Hunts I've Lived To Tell About.
Zaglis was first presented in "You Never Can Tell," a short story included as a companion piece in the 1994 sourcebook Galaxy Guide 10: Bounty Hunters. Rick D. Stuart authored the book, which was published by West End Games for use with Star Wars: The Roleplaying Game.