As if Infinity War wasn’t big enough, it originally included the introduction of the Living Tribunal! The character is arguably the 2nd strongest in all of Marvel Comics and his appearance could have led to some drastic changes to the Marvel Cinematic Universe. Christopher Markus and Stephen McFeely are the screenwriters behind Avengers: Infinity War and Avengers: Endgame (as well as Captain America: The Winter Solider, Captain America: Civil War) and revealed how they planned to introduce the character during an interview with the New York Times.
MARKUS We did try to put the Living Tribunal in the first movie (Infinity War). We wrote a scene in which he appeared during the Titan fight. And everyone was like, what?
McFEELY Whoa. He’s got three heads. It would indicate a whole different level of architecture to the universe and I think that was too much to just throw in.
MARKUS The idea’s still in [Marvel Studios President] Kevin [Feige]’s court.
The Living Tribunal is a major player in the Marvel cosmic universe, especially in The Infinity Gautlet comicbook series. The Living Tribunal is an entity that oversees and maintains balance in the realities that constitute the Marvel Comics Multiverse. As such, when Thanos gathers the Infinity Stones/Gems in an attempt to wipe out half of all living creatures, that causes the Living Tribunal to appear. The character casts judgement on Thanos but decides to let him wield the Infinity Gauntlet. However his powers are so vast and limitless that once the heroes triumph over Thanos, the Living Tribunal declares that no person can ever again wield all of the Infinity Stones/Gems.
With the news that Marvel Studios’ is planning a film based on the Eternals which will likely expand on the cosmic world, it’s not entirely off the table that the Living Tribunal may show up further down the line in the Marvel Cinematic Universe.