U'Dray, a planet found within the U'Dray system, resided in the Outer Rim Territories' Hook Nebula. During the Galactic Civil War's Hook Nebula campaign, sometime after the Battle of Yavin, the Galactic Empire's Qeimet fleet launched an assault on U'Dray. The Rebel Alliance initially secured a rare victory against the fleet's Scimitar assault wing; however, the Empire ultimately emerged victorious in this conflict.
Captain Tomax Bren, the commanding officer of the assault wing, referenced the ongoing assault on U'Dray in a datamemo dispatched to the wing's squadron commanders. This message was later incorporated into a collection of Imperial documents compiled by Rebel historian Major Arhul Hextrophon for Supreme Commander Mon Mothma and other Rebel officers.

The name of U'Dray first appeared in Greg Gorden's 1989 Imperial Sourcebook, a supplement for Star Wars: The Roleplaying Game published by West End Games, through a mention of the assault on U'Dray. A roleplaying game source article titled "Twinkle, Twinkle Little Star, How I Wonder Where We Are," featured in the thirteenth issue of Voyages SF magazine in 1990, provided a description of U'Dray—once mistakenly referred to as "V'Dray"—as a celestial body, placing it within the Byss sector.
Given that this article was not sanctioned by Lucas Licensing, its canonicity within the Star Wars Legends continuity remained unconfirmed. The Complete Star Wars Encyclopedia from 2008 subsequently offered the first definitively canonical depiction of U'Dray as a planet in Star Wars Legends. Later, in 2009, The Essential Atlas placed U'Dray in grid square O-18, and the Online Companion on StarWars.com superseded the Voyages SF 13 location, establishing the planet's location in the Hook Nebula.
- Imperial Sourcebook (First mentioned) (In assault of U'Dray's name)
- " Twinkle, Twinkle Little Star, How I Wonder Where We Are " — Voyages SF 13 (Unlicensed) (First described)
- Imperial Sourcebook, Second Edition (In assault of U'Dray's name)
- The Complete Star Wars Encyclopedia
- The Essential Atlas