Darth Sidious (Hologram) was released during the Episode 1 toy line in 2000. The character was seen in holographic form in The Phantom Menace and in The Revenge Of The Sith. Despite it's limited articulation, it's still one of the best sculpts created for Emperor Palpatine, even 14 years after it's release. It's a pretty simple figure overall with only 7 joints and no accessories (besides the Commtech chip). Palpatine stands very securely on his own without help from a display stand (his legs are one big block of plastic and can't be moved individually). In order to get the best translucent look for Sidious, try to have him displayed with a light shining at him from the bottom.
The evil and mysterious power behind the Trade Federation's blockade of Naboo, Darth Sidious appears over vast distances as a holograph in order to communicate to his many subordinates.