Who is 'The Watcher'? More about the unseen narrator in Marvel's 'What If...?'

Marvel's What If...? introduces a gargantuan new figure to the MCU: The Watcher. In the show's trailer, this unseen character (voiced by Jeffrey Wright) introduces us to the multiverse, to the idea that our universe is not unique and exists parallel to infinite other realities.

"I observe all that transpires here, but I do...