The King.

One thing you must do, is prevent the King of The World from taking power. When the aliens landed, they laughed at us because we hadn’t, after all this time, elected one planetary leader. So, we took genes from every race and region on the planet, whisked them together in a test tube, and grew our new leader up in the space lab (we couldn’t do it anywhere on earth, everyone would get upset that he wasn’t being raised in their own country, and this was the only way to be sure he wasn’t influenced or compromised). Anyway, he’s the son of mankind but also a bastard, you need to stop him. You’ll know how when the time comes.