And it's not Captain Marvel.
Speaking to Comicbook.com, he chose his MVP in the final, climactic battle of Avengers: Endgame, and the character's personal feelings of vengeance clearly had a bearing.
“Wanda Maximoff, who is probably near the upper echelons of power,” he said.
“I contend she would have taken down Thanos if he hadn’t called the [army]. Right? It was done.
“So her being the Scarlet Witch now... in a full sort of unabashed power-based [way], coming into the Doctor Strange movie, that is two heroes coming together in a fun way.”
She unleashes particular fury on Thanos in Endgame, following the events in Avengers: Infinity War, when the murderous titan took the life (and Mind Stone) from her lover, Paul Bettany's sentient android Vision.
And indeed, Elizabeth Olsen's Maximoff, with her superhuman matter manipulating powers did seem to have among the most profound effects on Thanos in both Infinity War and Endgame.
She is set to return in two iterations to the MCU – Firstly, as Feige says, as a supporting character in 2021's Doctor Strange in the Multiverse of Madness, and then also in her own series.
WandaVision, which will air on Disney's new streaming platform Disney+, will follow the travails of Maximoff and Vision.
It joins Marvel spin-off series for Tom Hiddleston’s Loki and another for archery nut Hawkeye.
The platform launches in America on 12 November. A U.K. launch date remains TBC.