The Watcher

Uatu, the Watcher, is one of an ancient race of cosmic beings sworn to observe the multiverse and never interfere with it. He looks in on every branching reality from outside of them, narrating what he sees, and keeps that oath for a long time, until an Ultron holding all six Infinity Stones threatens every universe at once. He breaks his vow to gather a team of heroes from across the multiverse to stop it, and having intervened once, keeps doing it, until the other Watchers imprison him and put him on trial. Captain Carter's team comes for him, he shares his power with them to fight back, and once the other Watchers are stripped of theirs, he spares them and offers to teach them to see the multiverse rather than just watch it. Captain Carter dies winning that fight, and he keeps Kahhori, Byrdie and Storm on to watch over the multiverse with him. Read more →

First turns up in What If...? (Season 1).