He Who Remains
The first variant to appear is He Who Remains, in Loki season 1, episode 6, "For All Time. Always." Loki and Sylvie cross the Void and reach a citadel at the end of time. They expect a tyrant. They find a calm, chatty man who eats an apple and knows exactly what they're going to say.
He tells the story. In the 31st century, a scientist discovered that other universes existed. Versions of him in each one made the same discovery and, instead of cooperating, went to war. He won, used the creature Alioth as a weapon and created the TVA to keep a single timeline, pruning any branch that could bring another variant of him back. The Time-Keepers were puppets. He was the one in charge.
The offer: Loki and Sylvie can take his place, or kill him and unleash the multiverse, the most dangerous versions included. Sylvie stabs him. Before he dies he says "see you soon." When Loki returns to the TVA, there's a statue of him where the Time-Keepers used to be.