Whoville, sometimes written as Who-ville, is a fictional town created by author Theodor Seuss Geisel, under the name Dr. Seuss. Whoville appeared in the 1954 book Horton Hears a Who! and the 1957 book How the Grinch Stole Christmas! with significant differences between the two renditions. Its denizens go by the collective name Whos, as in a plural form of the pronoun who.

Horton Hears a Who! is a children's book written and illustrated by Theodor Seuss Geisel under the pen name Dr. Seuss. It was published in 1954 by Random House. This book tells the story of Horton the Elephant and his adventures saving Whoville, a tiny planet located on a speck of dust, from the animals who mock him. These animals attempt to steal and burn the speck of dust, so Horton goes to great lengths to save Whoville from being incinerated.