Keiran Halcyon, a Jedi Knight of Corellian descent, was a male Human who served both the Jedi Order and the Galactic Republic. His service occurred approximately four centuries before the rise of the Galactic Empire and the commencement of the Great Jedi Purge.
After being discovered as Force-sensitive and consequently admitted into the Jedi Order's academy, Keiran Halcyon eventually triumphed in his Trials of Knighthood and was elevated to the rank of Jedi Knight by the esteemed Jedi High Council. Dedicating himself to the path of the Jedi Guardian through independent study, Halcyon distinguished himself as a Corellian Jedi, undertaking numerous missions focused on protecting his home system. A notable achievement includes his successful intervention in 380 BBY to dismantle the infamous and destructive Selonian cult of Afarathu. During the construction of his lightsaber, Halcyon incorporated a Durindfire crystal, imparting a distinctive silver hue to the blade. Furthermore, by utilizing Jedi techniques preserved within the Jedi Temple's Archives, Halcyon managed to create a lightsaber blade capable of extending up to 3 meters.
Generations after Halcyon's passing, his lineage produced at least two more Jedi: the renowned Jedi Master Nejaa Halcyon, who valiantly served during the Clone Wars, and Corran Horn. Horn's birth coincided with a period of galactic turmoil, as the Dark Lord of the Sith Darth Sidious prohibited Jedi training and sought to erase the Order's legacy from galactic records. However, with the Galactic Empire's downfall and the Jedi Order's resurgence, Horn became a member of the fledgling Order, adopting the name of his ancestor, Keiran Halcyon. Under the tutelage of Luke Skywalker at the Yavin 4 Jedi Praxeum, Horn eventually abandoned the alias and rose to prominence within the Jedi High Council.
Despite possessing strength in the Force, the Halcyon bloodline was known for having a relative weakness in telekinetic abilities, a skill commonly associated with Jedi. However, instead of being hampered by this perceived limitation, members of the Halcyon family who became Jedi amplified their talents in alter mind, granting them advantages in areas where other Jedi might be less proficient. Keiran Halcyon also demonstrated proficiency in the ability to absorb energy.
The Jedi Academy Training Manual erroneously claims that Keiran coexisted with Luke Skywalker and briefly served as his student, when in reality, he lived 400 years before Skywalker's birth. This inaccuracy stems from a retcon introduced in the book I, Jedi, which reveals that the Keiran Halcyon featured in the Jedi Academy Trilogy was actually Corran Horn, a distant descendant of the original Halcyon. Horn adopted the alias at Skywalker's suggestion to conceal his Jedi training from public knowledge.