General Nathan was an American army general who appeared in the episode Get Schwifty as the central antagonist.
General Nathan was present during the Pentagon meeting after a giant alien head had appeared in the Earth's atmosphere causing heavy natural disasters. He wanted to destroy the Cromulons with nuclear weapons. The President disagreed instead giving Rick Sanchez and Morty a chance to perform a song for the Cromulon.
Later, General Nathan was still fixed on his idea to use nuclear weapons against the aliens and attempted a coup against the President by knocking him out and launching the nuclear weapons before Rick and Morty's second performance. However, Nathan's missiles proved to be ineffective against the aliens, only angering them. Rick and Morty's new song still managed to satisfy their Cromulon audience, nevertheless.
After the Cromulons left, General Nathan attempted to murder the President but is zapped by Rick using his particle beam wristwatch.
General Nathan's overall appearance, way of speaking and manner is likely a reference to Gen. Buck Turgidson, a similar military character played by George C. Scott in the movie "Dr. Strangelove."