Who is Koyi Mateil in Revenge of the Sith?

This is Koyi Mateil

Koyi Mateil - Revenge of the Sith
Are they real or are they just spectacular?

Twi'lek ‘Koyi Mateil ‘made a brief appearance in prequwl Revenge of the Sith during the scene at the Galaxies Opera House just prior to the Emperor explaining the Tragedy of Darth Plagueis to Annakin.
She is the wife of Duke Teta according to Starwars.com.

The scene was notable for being when Palpatine revealed to Anakin he could help save Padme from dying and now infamously supplying the knowledge that Twi'leks are no strangers to getting breast implants…in space.

Who played Koyi Mateil in Revenge of the Sith?

We cannot find any reference on the net for the actress who played Koyi. 

It may have been Nathalie Cox as an uncredited extra. However, we suspect given Revenge of the Sith was filmed in Australia, it's likely the extra was an uncredited model.

The character's name was first used by the 2017 reference book Star Wars: The Visual Encyclopedia. It's not canon but it's the best we have from an official source.

Paul Rose Jr has worked as TV News Producer, Forensic Analyst, and Train Conductor, among many other things. He’s the former TV Editor for Infuzemag.com and owns more books, DVDs, and comics than most people have seen in their lifetimes. When he’s not writing articles, he exercises his creative muscle writing screenplays and acting in film and television in Los Angeles, CA.