The President of Earth is a character in the Captain Proton holodeck serial, played by the Doctor in Bride of Chaotica! so that he can negotiate with photonic aliens.
The President of Earth is a role in The Adventures of Captain Proton, Tom Paris's homage to old science fiction serials, and features in the fifth-season Voyager episode Bride of Chaotica!
Visitors from a dimension where all life is photonic stumble into the running programme and take it for reality, going to war with the villain Doctor Chaotica. They cannot even register organic beings as alive, so the crew need an envoy the aliens can see.
The Doctor, himself made of photons, is sent in as the President of Earth, complete with period costume. He talks to the aliens' representative and wins their co-operation while Captain Janeway, as Queen Arachnia, deals with Chaotica.