First Appeared: Horton Hears a Who! (1954)
Founding Father: Dr. Seuss
Notable Residents: Cindy Lou Who, the Grinch, Augustus Maywho

Whoville is one of the few cities within the Dr. Seuss universe that accumulates any sort of detail—enough detail, in fact, for it to appear in two separate books, each with very different stories to tell. Whoville sits on a speck that rests in a flower, in the case of Horton, or on a snowflake, in the case of the Grinch. Because the city is mobile in this way, it remains extremely variable and subject to all sorts of conditions. Whoville features a mountain on one side, where the Grinch and his dog Max reside. It's a city known for the kindness of its inhabitants, especially Cindy Lou Who, who makes the Grinch's heart swell. And also the mayor of Whoville, who organizes the citizens to shout loud enough to prove to the jungle animals that their city exists, no matter how small it is.