The Kashyyyk Massacre was an atrocity instigated by Greiko Lornan on Kashyyyk in 12 ABY. After the departure of Danik Kreldin and Fianar Reanus from the Neo-Imperial Movement, Greiko took control over the organization and drastically turned the Movement's goals around; rather than fighting the war against the Galactic Empire, Greiko waged a terror campaign against the New Republic and its allies, starting with Kashyyyk.
A summit was being held on Kashyyyk, with many Republic officials and Jedi in attendance. Lornan launched his attack, his soldiers killing hundreds of innocents and attendees, including destroying an orphanage. The Neo-Imperials exercised no discrimination in their slaughter, and they all escaped before the Jedi and Republicans could launch a proper counter-attack.
The attack greatly tarnished the Neo-Empire's reputation, forcing Kreldin and Reanus to return and attempt to regain control over the organization, resulting in the Neo-Imperial Movement Mutiny. They sought to apologize for the attack on Kashyyyk, donating thousands of credits to restoration efforts on Kashyyyk and offering to hand over Lornan to stand trial.