The Marvel universe is absolutely, agonizingly massive, with completely different areas and timelines thanks to the magic of multiversal story-telling. Recently, nearly every possible arc which could be adapted has been adapted for the Marvel Cinematic Universe, including the introductions of Kang the Conqueror and his many, many variants — such as Immortus.
But who exactly is Immortus, and what makes him different from the other evil, cape-wearing villains?
The alias of Immortus belongs to one of the different variants of Nathaniel Richards, one of Reed Richards’ descendants some 1000 years later. After he invents time-travel and goes back to Ancient Egypt to become Rama-Tut, he becomes jaded and cynical over the deaths of his son and partner Ravonna, which occur without fail every timeline.
Rama-Tut then accepts a role with the Time Keepers to protect timelines instead of conquering, as almost all Kang variants are inclined to do. For those who have seen the Loki series, this is what He-Who-Remains is based on for the most part. Immortus becomes a foe for the Avengers regardless, with him playing a part in creating Vision after experimenting on the original Human Torch (who his variant, Victor Timely, created).
Immortus isn’t quite a villain like his other variants, often more of an ends-justify-the-means protector, although he does kill Iron Man and Hulk before the Young Avengers, well, avenge their deaths. Within the Kang dynasty, he’s typically the most likely to not be a total sociopath, but who knows what the MCU has in the works for him.
Jonathan Majors portrays Immortus in the post-credits sequence of Ant-Man and the Wasp: Quantumania.