Horton Hears a Who is a children's book by Dr. Seuss, which was published in 1954 by Random House. The book is the sequel to Seuss's Horton Hatches the Egg from 1940.

Horton Hears a Who has been adapted into two animated shorts, one by Chuck Jones in 1970 and another by Russian director Alexei Karayev in 1992. In 2008, the book was adapted into a full length animated feature which starred Jim Carrey and Steve Carell.

Horton Hears a Who is about an Elephant named Horton who discovers a community named "Whoville," which resides on a speck of dust. Horton vows to protect the residents of Whoville from danger, which primarily comes in the form of Vlad Vladiikoff and Sour Kangroo.

Many Pro-Life groups have adopted a line from the book, "A person's a person, no matter how small" for their cause. Dr. Seuss's wife, Audrey Geisel, has spoken out against these groups, saying that she "doesn't like people to hijack Dr. Seuss characters or material to front their own points of view."

• • Mahalo's Guide to Dr. Seuss
• Seussville
• Wikipeida: Dr. Seuss
• Dr. Seuss Art
• Wikiquote: Dr. Seuss
• The Dr. Seuss Web Page