Avengers: Endgame almost featured Thanos (Josh Brolin) meeting The Living Tribunal. Directed by Joe and Anthony Russo from a screenplay by Christopher Markus and Stephen McFeely, Avengers 4 not only had to act as a direct sequel to Avengers: Infinity War, it also had to culminate everything that transpired in the Marvel Cinematic Universe up to that point. And since Thanos was the primary bad guy of The Infinity Saga, fans expected him to play a significant role in the movie.
Yet, while he remained to be the story's antagonist, the Mad Titan's screen time was drastically scaled down to put focus on the heroes. This understandably saddened fans who were wanting to see more of the MCU's Thanos, but it makes sense considering the type of feel the filmmakers were going for with Endgame. Among one of the deleted scene focusing on the Mad Titan would've officially introduced The Living Tribunal in the MCU. Apparently, Thanos was originally going to be confronted by the Marvel entity as he's judged for his crimes.
During their Hall H panel (which Screen Rant attended) at San Diego Comic-Con titled "Writing Avengers: Endgame," Markus and McFeely revealed details of what would've been The Living Tribunal's role in the culminating project - a bit that was ultimately edited out of the movie's theatrical cut. The Mad Titan was supposed to be held accountable for his atrocities and, "in the end, he would have been dumped in front of the Living Tribunal, who judged him guilty."
"It was partly inspired by Kevin Feige... he came into the conference room in Atlanta, where we were trapped for years, and he had brought a bunch of comics panels with him... we were pretty far down the road... and he wanted to make sure we didn't lost the psychedelic nature of the [Jim] Starlin universe... and so we stuck the Living Tribunal in the movie. So, as Thanos and Doctor Strange came to blows, Doctor Strange blew Thanos' mind and sent him through the mindscape."
In the comics, the three-faced entity is responsible for overseeing Marvel Universe's alternate dimensions. He allowed Thanos to seek ultimate power believing that it is the natural progression of things. Originally, The Tribunal was also the one who ordered the Infinity Gems to be separated and never be reunited again. The character was name dropped in Doctor Strange with a weapon found in Kamar Taj apparently called “The Staff of the Living Tribunal,” although it's unknown if it has any connections to the being.
Frankly, the described scene sounds so fascinating, and fans wouldn't be opposed to seeing it on Avengers: Endgame's home release. Despite being involved in one of the most creative fights in Infinity War, Doctor Strange (Benedict Cumberbatch) didn't do much during the movie's final action set piece, and learning that he was somehow linked to this bit only for it to be cut out is quite disappointing. Considering that the scene may have been shot, this wouldn't be too difficult to pull off. Although, Marvel Studios might want a character like The Living Tribunal's first MCU appearance to play out first on the big screen.