Who knows that the Emperor is the Sith Lord Darth Sidious? And when?

32 BBY
Nute Gunray and his cronies - know that Darth Sidious is a Sith Lord and that his apprentice is Darth Maul [TPM]

Darth Maul - Sidious's apprentice [TPM]

Darth Plagueis - Sidious's Master [ROTS]

Darth Tyranus - Sidious next apprentice [AOTC]

22 BBY
Obi-Wan (and the Jedi) - Count Dooku tells Obi-Wan that the Republic is under the control of a Dark Lord of the Sith named Darth Sidious. The Jedi aren't sure whether or not to believe him but Yoda warns that they must be cautious of the Senate. [AOTC]

20.5 BBY
Ronhar Kim and Tap-Nar-Pal - "He knew... he found out... you were... right... my friend." Then Ronhar Kim dies.

< 19 BBY
Mas Amedda and Sly Moore - have known Palpatine's Sith identity. Amedda is present when Yoda confronts Sidious. [SWI84]

Fenn Shysa and Tobbi Dala - know Sidious and Palpatine are the same [SWI80][MCSW]

19 BBY
Commander Valient and Captain Dyne - after obtaining evidence from Nute Gunray's mechno-chair, the Republic embarks on a search for the elusive second Sith. Valient and Dyne and their team follow the trail to the subbasements of 500 Republica. There they come face-to-face with Darth Sidious. [LE]

Anakin Skywalker - Palpatine convinces him to become his Sith apprentice

Mace Windu, Kit Fisto, Agen Kolar, Saesee Tiin - go to arrest Palpatine after Anakin tells them that he is a Sith Lord

Obi-Wan Kenobi, Yoda - learn the truth about Anakin and the Sith from a hologram viewed at the Jedi Temple

Padmé Amidala - learns the truth about Anakin from Obi-Wan which she confirms when she confronts Anakin on Mustafar.

Bail Organa - rescues Yoda following his duel with Palpatine. Agrees to protect baby Leia from Vader and the Emperor.

Qui-Gon Jinn's spirit - knows all sometime after Sidious reveals himself. [ROTS]

Senate - When presenting evidence of the Jedi rebellion, the Senate hears an audio recording of the Jedi's attempt to arrest Palpatine. Mace Windu accuses Palpatine of being a Sith Lord, which Palpatine neither confirms nor denies. [ROTSN]

? BBY
Mara Jade - Emperor's Hand [HE]

3 ABY
Luke - Yoda and Obi-Wan's spirit tell Luke of how Vader was lost to the Emperor. [ESB]

SOURCE CODE KEY
AOTC Attack of the Clones
ESB The Empire Strikes Back
HE Heir to the Empire
LE Labyrinth of Evil
MCSW [Marvel Comics - Star Wars]
RJ Return of the Jedi
ROTS Revenge of the Sith
ROTS Revenge of the Sith novelization
SWI Star Wars Insider
TPM The Phantom Menace

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Who Knows Which Secrets? thread