We lovingly refer to the Narrator as the pointy-hand man because, well, all we see of him is a disembodied pointy-hand. Being the yin to Marvin's yang, his talking consists of the entire poem, but we hardly get to see any of him in the illustrations. Guess we'll just have to make due, dig deep, and see what we can find.
Marvin K. Mooney may have his name in the title of the book, but this poem belongs to the Narrator. It's his show; Marvin K. is just along for the ride. Literally.
See, the illustrations all show Marvin K. Mooney riding all those fabulous rides (eat your heart out, Disney World!). But it's the Narrator who comes up with all this fabulous imagery. He puts all that wackiness into modes of transportation—from cow to fish to Ga-Zoom. They all come from his imagination. (Want to know more about those crazy ways for Marvin to get around? Then don't forget to surf your way over to our "Symbols" section.)
Also, the Narrator is responsible for the building intensity of the poem. Each time Marvin K. refuses to leave, he increases the level at which he tells the boy in purple to get gone. It goes from a simple "Just go" (6) to "Just go, go, GO!" (39) to "I don't care / how you go. / Just GET!" (69-71). His voice brings this building intensity to the poem, preventing the repetition of a simple theme—time to go—and giving it that fun, insane quality.
Marvin K. could be read as representing Richard M. Nixon. Seuss thought it was time Nixon left the White House, and Marvin K. Mooney Will You Please Go Now! was his way of asking—albeit in code—for Nixon to resign. But if Marvin K. symbolizes Nixon, then whom does the Narrator represent?
Well, that kind of depends on how you read history. The Narrator could be Seuss himself. He wrote the book. The words technically do belong to him. Just remember: you must always be careful when assuming an author and a narrator are the same person. We're not saying they can't be; just don't assume they always are.
Another possibility is the American people as a whole. America wasn't too happy with Nixon in the time leading up to his resignation—what with the illegal wiretaps, the breaking and entering, and, for flavor, anti-Semitic tendencies (source). All types of people from all walks of life were ready to see Nixon leave office. Sure, some Americans wanted Nixon to stick around, but that doesn't mean the Narrator still can't represent the voice of the American people.
But that was back in 1972. Today, our Narrator doesn't have to be the American people specifically. Perhaps he is anyone who desires to see Nixon, or any crooked con of a politician, leave office. This can certainly be accounted for by the number of people after Seuss who took Marvin K. Mooney and made it their own rally call for another politician to resign. Don't believe us? Check out our "Brain Snacks" section for more.