Great Schism is a term that has been used to describe at least a couple of events in the history of the Jedi Order. Within the Chamber of Antiquities, located in the lower levels of the Great Jedi Library on Ossus, there were many old heritage tapestries that showed the first two Great Schisms of the Jedi Order.
The Nexus of Power sourcebook, which was released by Fantasy Flight Games in 2016 for the Star Wars: Force and Destiny roleplaying game, was the first time that the Great Schisms were mentioned in canon. In Star Wars Legends, the comic Tales of the Jedi – The Golden Age of the Sith 0, written by Kevin J. Anderson, with art by Dario Carrasco, Jr. and published by Dark Horse Comics on July 1, 1996, was the first appearance of the First Great Schism. The reference book The New Essential Chronology, published in 2005, clarified that the First Great Schism and the Second Great Schism were distinct occurrences, and that the subsequent century of conflict was the same event as the Hundred-Year Darkness. The Hundred-Year Darkness has since been brought back into current canon, but its relationship to the Great Schisms has not been established.