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Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] What assassination attempt(s) - in Canon & Legend - was closest to killing Emperor Palpatine?
gpt
[*Legends/Expanded Universe* canon]

* In the first year of the Empire; a coup on Coruscant lead by headmaster Gentis of the Imperial Academy managed to critically wound the Emperor with an airborne toxin. (*Darth Vader and the Ghost Prison*)

* About two years before the Battle of Yavin; Galen Marek aka Starkiller, Lord Vader's "secret apprentice" turned rebel seemingly got the best of Palpatine in a fight.  But Marek chose mercy rather than striking down a defenseless foe.  But considering the Emperor never even drew a lightsaber in that encounter, it's unclear if he was truly defeated or just faking it. (*The Force Unleashed*) 

* Several weeks before the Battle of Yavin; in a coup attempt orchestrated by Grand Moff Tracta, Moff Kadir rushed Palpatine's throne room with a contingent of secretly conditioned Stormtroopers. A few Royal Guards died and Palpatine suffered a minor injury from Kadir himself. (*Empire vol 1: Betrayal*) 


* About three years after the Battle of Yavin; Grand Admiral Zaarin waged a military insurrection. At one point the Emperor was taken captive by Arden Lyn a Force-nullifying transport. (*Tie Fighter*.  *The Emperor's Pawns*)

* At the Battle of Endor; Darth Vader chooses to save his son and throws the Emperor down a reactor shaft, destroying his body.  But Palpatine's spirit endures in a harrowing ordeal, his essence is carried for a time by an Emperor's Hand agent and then is ritually transferred into a clone of Palpatine's original body. (*Return of the Jedi*.  *The Emperor's Pawns*.  *Dark Empire*)