Very little is known officially about Darth Sidious. Lucasfilm has registered the domain names www.darthsidious.com, darth.net, sith.net, darthsidious.net and they links back to the offical site. Lucasfilm has also registered the name "Darth Sidious" in the US Trademark Database.

George Lucas said the following in the February 1999 Vanity Fair:

Given that THE PHANTOM MENACE is a Vader- and Emperor-free movie, the role of evil string-puller falls to someone we've never heard of. "The phantom menace is a character named Darth Sidious," Lucas says, "who is the last of the Sith." Actually, Lucas goes on to explain, the "menace" honorific should be broadened to include Sidious's apprentice, Darth Maul, a terrifyingly fierce-looking character played by martial-arts expert Ray Park. Maul gets to fight a lightsaber battle with Obi-Wan, but Sidious remains a shadowy figure. "Nobody knows Darth Sidious exists," says Lucas. "Well, he's seen to the audience, but not to the players."

On a more Unofficial/Official Note, Master K got pictures of these prototype Darth Sitious Figures. They confirm his resemblance to the Emperor of the classic Trilogy.

The following text comes from the Darth Sidious action figure:

"Cloaked in flowing robes and shrouded in evil, Darth Sidious is a Dark Lord of the Sith and the mysterious power behind the Trade Federation's blockade of Naboo. As he conspires and manipulates, he keeps his presence - and his true intentions - well hidden."

This shows that Sidious is the one in control of the Federation, not the Nimoudians.

11/2/98 - From an informant:

He is seen in person and he looks almost exactly like the Emperor in the original trilogy. He has a black hood. Only lower half of his deadly white face is visible. Also his voice is very similar to Emperor's in ROTJ.

Valorum: Darth Sidious appears in this film mostly as a holo-projection, as the Emperor did in The Empire Strikes Back. He issues orders to Darth Maul, who seems to be his underling.

Mode - Mode has been a reliable source for us, but some of the information in the following report is accurate, while other parts are a little mixed up. We present to you all the reports we got so you can puzzle it out for yourself.

7/24/97 - The designers at ILM have been working on final designs for MANY DIFFERENT Dark Sith Lords. Apparently the recurring theme is that of the Darth Vader-style helmet. They all seem to have the same curved helmet with different masks and space-suits/uniforms. There are 12 different designs for 12 distinctly different characters. These 12 sith lords might possibly correspond to the rumor about the 12 Yodas. From what my source has been able to tell, these 12 sith lords are kind of the guardians of the force. The "Supreme Court" of the Jedi, if you will. They act as a panel that regulates the Jedi and punishes dark Jedi. These Sith Lord costumes are merely uniforms; not mechanical prosthetics as in Vader's case."

Hmmmmm. We thought that the Sith Lords were Dark Jedi who were a weird offshoot of the Jedi. Why would they be judges of the Jedi Knights? Still, it would make sense that Vader would be allowed to hunt the Jedi down if he were their judge, right? Is what we thought wrong or is the info warped? We will soon find out! Also, remember when we reported that they were making a LOT of Vader and Mandalorian costumes? Do these bits of info jive?

7/29/97 - The mysterious Mode returns. In light of questions about the 'Sith Lords', we asked him to tell us more about this. Are they really Sith Lords? Here's his reply:

"I called them Sith lords because I just assumed that all characters in a Vader-like costume were Sith Lords. Think of the characters as "Master Samurai". What you were saying is true, that when a jedi reaches a certain level, he/SHE gets to wear the cool uniform. From what I have been told, the uniform is kind of like a jedi's supreme court robe. I was a little hasty in applying MY term to these judges. They have been called "The Council." I have another tasty bit of info for you all: One of the most powerful Jedi among the Council is a WOMAN!! I don't know her name, but she wears one of the Vader costumes."

Hmmm, interesting! Verrry Interesting! So, Vader's costume is not necessarily a Sith Lord costume!

12/17/98 - T'Bone posted a news item saying that Palpatine and Sidious are both played by Ian McDiarmid. This has been a point of speculation for some time, so it's good to see some spy address it. Chryen sent us the following note that seems to back up the notion (note it was sent earlier in the week):

This is Chyren here. In response to heated rumours on the Force.net Prequel Forum over the precise relation of Sidious to Senator Palpatine, I created this comparative image with the screenshots of Sidious and Palpatine from their action figure packaging, shots of the known Emperor from ROTJ, and blown up sections of their features for closer comparison.

http://www.jediknight.net/jkmag/bfp2/0compare1.gif

Notice that the shiny dragon clasp the Emperor wears at his neck is identical to that worn by Sidious.

I created this late on the 14th. Ironically on T'bone's Prequel Preview site, he later confirmed that McDiarmid is actually also playing Sidious. I stress that my image was created before this info was released, and was posted on both the Prequel Forum at your site and at The Virtual Edition's forum around 9.45 pm last nite.

So, as you see, a lot of people were all thinking along the same lines. It also makes sense if you look at other evidence. I mean, we've got names of every actor playing every character EXCEPT for Darth Sidious. Exploring the possibilities, I'll offer up another bit of speculation. Look at the Darth Sidious figure and the Senator Palpatine figure. Note how much more wrinkled Sidious is than Palpatine? If they are the same guy, why is one wrinkled by the Dark Side and the other not? Could it be that one is the clone of the other? After all, in the Dark Empire comic by Tom Vietch, the Emperor was resurrected as a clone. Before you snort and make cracks about what's canon and not, take note that Lucas himself approved Veitch making an Emperor clone. Not only that, Lucas reportedly told Veitch he loved the story. (Remember that Tales of the Jedi had a double bladed lightsaber first, as well.) Would that inspire a Sidious/Palpatine connection and make a good lead into the Clone Wars? Who knows! But it's fun to kick around ideas.