The Kree Supreme Intelligence was played by Annette Bening in Captain Marvel, but early plans for the movie would have had the AI leader present itself as a giant, green head - just like in the comics. In both the comics and the Marvel Cinematic Universe, the Supreme Intelligence is a being created to further the interests of the Kree and help them win in their war against the Skrulls, but in the MCU the Supreme Intelligence takes on different forms depending on who it's speaking to.
Captain Marvel first visits the Supreme Intelligence at the very start of the movie, when she's still a Kree Starforce operative called Vers who had no recollection of her past. The Supreme Intelligence manifested in the form of Mar-Vell - though Carol didn't actually know who she was at the time. Mar-Vell was a Kree scientist who aimed to end the Kree-Skrull War by using the Tesseract to create a light-speed engine, and gained access to the Tesseract by posing as a S.H.I.E.L.D. scientist called Wendy Lawson. It was in this role that she first met Carol Danvers, who was a US Air Force pilot tasked with test flights for Lawson's experimental planes.
Speaking to ComicBook.com, Captain Marvel production designer Andy Nicholson said that the idea of having the Supreme Intelligence be comic book accurate "came and went" and that "at one stage, it was part of the movie." However, it was ultimately decided that having Carol argue with a big, green, floating head at the emotional climax of the movie would have been a little distracting:
"It was there. We did develop a line where within that space from the big pool of water in the back of the room, that eventually, that's where the big green head would come out of. I think eventually for the final scene of the movie, it would've taken away from what was the core focus which was, it would've been a big spectacle which would've overwhelmed the main thrust of what we were doing which was talking about Carol's development and transformation into Captain Marvel."
Visual effects supervisor Janelle Croshaw additionally told Screen Rant:
You know, there might have been [consideration of including the Supreme Intelligence's original comics design]. I think that all of those avenues were explored. What it comes down to is, at that moment, it's about her turning into Captain Marvel and finding her own power within herself and not from someone else. So, I think that as the film evolved, we asked what are the most important parts that need to be there for that to be conveyed? Sometimes the script, early versions even, are trying to cram in so much that it almost complicates the whole thing. So you have to get down to the core of what's necessary for the film.
Captain Marvel is forced to visit the Supreme Intelligence again at the end of the movie, and they engage in a battle of wills until Carol realizes that the Kree didn't give her powers - they were actually holding her back. Upon this realization she is able to evolve to her full Binary form, which proved to be particularly devastating to Thanos' ship in Avengers: Endgame.
It's still possible that we'll see the Supreme Intelligence's "true" form revealed in a future MCU movie, though Captain Marvel implied that the AI doesn't really have a true form. The Kree interact with their leader by being plugged into a virtual environment, so the Supreme Intelligence can take on whatever appearance it believes will have the greatest impact on its visitor. The giant green head, while it might have looked cool if executed properly, doesn't emotionally connect to Carol on the same level as having the Supreme Intelligence take the form of her mentor.
Source: ComicBook.com
