MCU: 8 Villains Who Could Be The Next Big Bad
6. Thane
Imagine in the aftermath of the battle with Thanos, after the death and destruction is finally over and our heroes have been taken to their very limits, it is revealed The Mad Titan has a son. This kind of cliffhanger ending to Avengers 4 would show that the MCU has no intention of slowing down post-Thanos.
While Thane is considerably smaller in stature than his father, he is no less evil or violent, and would pose a new, yet all too familiar threat to The Avengers.
The MCU could take Thane's character arc one of two ways. The son could be outraged by his father's defeat and swear to avenge him and finish his work, or Thane could hate his father so much that his goal is to better his every action. If Thanos almost defeats The Avengers it will be Thane's mission to defeat them completely.
The latter is more likely as this is closer to the source material. In the recent Thanos comic arc Thane has gone so far as to try and kill his father himself.
Within the MCU Thane could resent his father for the attention given to his adopted siblings and not himself. Gamora, Nebula, and The Black Order will have all been introduced into the universe by this point, with Thane remaining in the shadows.