At what point in the prequels is it revealed that Palpatine is Darth Sidious?

Question

In Episode III, Anakin discovers that Palpatine is the Dark Lord of the Sith and Mace Windu goes to arrest him. Anakin accuses Palpatine, "You're a Sith lord." and Palpatine doesn't deny it. Is this the earliest point that the movies explicitly state this?

I know there are a lot of hints that happen before this:

• Sidious and Palpatine are both played by Ian McDiarmid, although this isn't mentioned in the credits. Episode II credits Christopher Lee as "Count Dooku / Darth Tyranus" but Ian McDiarmid is just credited as "Supreme Chancellor Palpatine".
• Episode one does a suspicious cut to Palpatine's face when Mace Windu is speculating as to whether Darth Maul was the apprentice or master sith.
• Earlier in Episode III, Palpatine is talking to Anakin about Darth Plagueis.

Just counting the movies themselves (not the novelizations or any other surrounding content), is there any earlier point in the prequels than Anakin's accusation in Episode III where it is explicitly mentioned that Palpatine is Darth Sidious?

Answer 1

The confrontation in Episode III that you mention is the first time in the prequels that there is definitive proof that Palpatine is also Darth Sidious. Even the scripts for Episode I, Episode II, and Episode III keep the characters separate until just after the confrontation (when Anakin is given the name Darth Vader). At that time the Episode III script itself indicates that the two characters are the same:

PALPATINE is putting on his dark cloak: he is now fully DARTH SIDIOUS.

Of course, there are plenty of clues that Palpatine is Sidious before that. The first clue is at the beginning of Episode I, when Sidious tells the leaders of the Trade Federation that

I have the Senate bogged down in procedures.

The Senate connection is not available to the Jedi until later, when Darth Tyranus tells Obi-Wan that

Hundreds of senators are now under the influence of a Sith Lord called Darth Sidious.

This is the only real clue available to the Jedi Order until the actual reveal in Episode III, except for Anakin who -- as you mentioned -- also learns that Palpatine has knowledge of Darth Plagueis.

As for the audience, there are other clues available -- the ones you've mentioned, the fact that Sidious and Palpatine look similar (since they are played by the same actor), the musical themes common to Sidious and Palpatine, the fact that in the original trilogy the Emperor is named Palpatine and is obviously a Sith Lord, etc. An astute viewer would thus be able to figure out with high confidence that Palpatine is Sidious before the explicit reveal.

Answer 2

In the prequel films themselves, no. As you mention, prior to Anakin saying so, there's no explicit confirmation that they're the same person, though there are plenty of hints (same actor, same chin, same balcony railing in TPM, and so on).

In fact, as far as I know, there wasn't any unequivocal confirmation that they're the same person in all of Star Wars media up until Revenge of the Sith and its tie-in material in 2005. It was known that Chancellor Palpatine was the same person as Emperor Palpatine, and that the Emperor was a Sith Lord, but official material stopped short of saying whether he was the Sith Lord Darth Sidious. They're listed as separate people in 2002's The Essential Guide to Characters, and novels like Darth Maul: Shadow Hunter rely on the dramatic irony of Sidious's identity, but stop short of spelling out that they're the same person.

Here's a roundtable discussion from July 1999 among several professional Star Wars authors and fans, showing that even they didn't know for sure that Palpatine = Sidious as of the release of The Phantom Menace:

Jeff Boivin: A friend pointed out to me that at the end of TPM, when Palpy lands on Naboo,the whole Jedi Council is present. If Palpy WAS Sidious, somebody would sense him! This supports Rich's (I think) theory of Palpy being a clone of Sidious, which Sidious helps rise to the role of Supreme Chancellor so he can take over.

Abel Pena: The Jedi Council thing is absolutely correct. And I go for the "Palp-ain't-Sidious" theory too. Futher support: Amidala tells Senator Palpatine she's going back to Naboo. But when the Neimrods get word and tell Sidious, he says something like "this is an unexpected move."

Bob Lippman: Palpatine surely wants to keep his true identity a secret from the Nemoidians, especially as he knows that in all likelihood their blockade will fail and their federation will crumble. He is merely sacrificing them. No need to give them too much information, lest they turn him in when they fall. Far better to create an alter-ego, i.e., Darth Sidious, to keep his true identity a secret from his cohorts. Even Darth Maul may have had no idea who he was ultimately working for.

GhentZ: This never occurred to me (the creation of an alter ego to throw the Neimoidians and anyone tapping into the communications off the trail), but it makes perfect sense and is a scheme worthy of good ole Palpy.

_{(Source: http://www.myuselessknowledge.com/swfa/TC-2.html)}

Answer 3

Episode III drops all sorts of hints to Anakin in-universe. The first serious one happens in the opera house (transcript)

PALPATINE: (continuing) Did you ever hear the tragedy of Darth Plagueis "the wise"?

ANAKIN: No.

PALPATINE: I thought not. It's not a story the Jedi would tell you. It's a Sith legend. Darth Plagueis was a Dark Lord of the Sith, so powerful and so wise he could use the Force to influence the midi-chlorians to create life ... He had such a knowledge of the dark side that he could even keep the ones he cared about from dying.

ANAKIN: He could actually save people from death?

PALPATINE: The dark side of the Force is a pathway to many abilities some consider to be unnatural.

ANAKIN: What happened to him?

PALPATINE: He became so powerful . . . the only thing he was afraid of was losing his power, which eventually, of course, he did. Unfortunately, he taught his apprentice everything he knew, then his apprentice killed him in his sleep. (smiles) Plagueis never saw it coming. It's ironic he could save others from death, but not himself.

ANAKIN: Is it possible to learn this power?

PALPATINE: Not from a Jedi.

For being a normal politician he sure seems to know a lot about the Sith. And the Force. Hmm. Oh, well, I guess he's just saying it for fun or something... Whatever. I'm sure he's still just some nice old man.

Until we get to this scene in Palpatine's office. It turns out Anakin is kinda dense (emphasis mine)

PALPATINE: It is upsetting to me to see that the Council doesn't seem to fully appreciate your talents. Don't you wonder why they won't make you a Jedi Master?

ANAKIN: I wish I knew. More and more I get the feeling that I am being excluded from the Council. I know there are things about the Force that they are not telling me.

PALPATINE: They don't trust you, Anakin. They see your future. They know your power will be too strong to control. Anakin, you must break through the fog of lies the Jedi have created around you. Let me help you to know the subtleties of the Force.

They walk into the hallway.

ANAKIN: How do you know the ways of the Force?

PALPATINE: My mentor taught me everything about the Force . . . even the nature of the dark side.

They stop.

ANAKIN: You know the dark side?!?

PALPATINE: Anakin, if one is to understand the great mystery, one must study all its aspects, not just the dogmatic, narrow view of the Jedi. If you wish to become a complete and wise leader, you must embrace a larger view of the Force. Be careful of the Jedi, Anakin. (pausing) They fear you. In time they will destroy you. Let me train you.

ANAKIN: I won't be a pawn in your political game. The Jedi are my family.

PALPATINE: Only through me can you achieve a power greater than any Jedi. Learn to know the dark side of the Force, Anakin, and you will be able to save your wife from certain death.

ANAKIN: What did you say?

PALPATINE: Use my knowledge, I beg you . . .

ANAKIN: You're a Sith Lord!

ANAKIN ignites his lightsaber.

PALPATINE: I know what has been troubling you . . . Listen to me. Don't continue to be a pawn of the Jedi Council! Ever since I've known you, you've been searching for a life greater than that of an ordinary Jedi . . . a life of significance, of conscience.

ANAKIN: You're wrong!

PALPATINE: Are you going to kill me?

ANAKIN: I would certainly like to.

PALPATINE: I know you would. I can feel your anger. It gives you focus, makes you stronger.

At this point there's no more doubts that Palpatine and Sidious are one and the same. The only other Sith lord was Count Dooku (Darth Tyranus), and he's already dead. If that wasn't obvious enough, however, this scene removes any doubt

MACE arrives with THREE JEDI to arrest PALPATINE.

PALPATINE: Master Windu. I take it General Grievous has been destroyed then. I must say, you're here sooner than expected.

MACE WINDU: In the name of the Galactic Senate of the Republic, you are under arrest, Chancellor.

MACE WINDU and the other JEDI ignite their lightsabers.

PALPATINE: Are you threatening me, Master Jedi?

MACE: The Senate will decide your fate.

PALPATINE: (burst of anger) I am the Senate!

MACE: Not yet!

PALPATINE stands, a laser sword appears out of his cloak sleeve, and he spins toward the JEDI.

Not only does Palpatine whip out the trademark red lightsaber, he goes all-in on a 4v1 lightsaber duel and kills three of them almost instantly. After Anakin finally turns on Mace Windu, Windu is killed and there's nothing left to doubt. Palpatine bestows the name Darth Vader on Anakin and tells him to kill the Jedi at the temple.

Answer 4

I had the VHS in France, it was clearly stated at the back, describing the synopsis : "Anakin Skywalker is still a young boy and Palpatine is not yet the cruel Emperor"