Artificial soul creation.
Current day politicians would probably suffer an allergic reaction if he tried to possess them. Similarly, I would suspect direct possession of the living would lead to problems down the line so it would probably be better kept to a minimum.
Thus my villain's first step would be to call up James Randi and win $1 million for "bringing the dead back to life."
He would then repeat these 'miracles', bringing the dead back to life for their loved ones in order to deliver reassuring pablum on national TV, sort of John Edward with zombies.
After amassing enough money and fame, my villain would place a soul in Oprah Winfrey. There should be no resistance, as everyone knows she sold her soul to the dark lord Deepak Chopra decades ago.
Using the power of Oprah he would start a political campaign to bring more "spirituality" into American politics, as well as lobbying for the sentient dead to have the right to vote.
He would thus eventually win the presidency of the United States, as there are not a lot of people who wouldn't vote for him after getting a touching, or terrifying (lets not prejudge relationships) phone call from their dead grandmothers talking about how he is chosen by God to lead the country.
With America under control, similar campaigns would be launched elsewhere, slowly replacing world leaders with elected ensouled automatons.
This may take longer than the two terms allowed under US law - but given the nature of the power, setting up a replacement would probably be easier than setting up a constitutional amendment.
Eventually world conquest would be achieved, not through violence but through emotional manipulation and political machination.
![Sea[L]ix](https://eg-forums-escapist-data.nyc3.digitaloceanspaces.com/data/avatars/l/183/183150.jpg?1621239097){kind=avatar}
