Glenn Franklin Howerton III was born in Japan on April 13, 1976, the son of American parents Janice and Glenn Franklin Howerton Jr. His father was a fighter pilot. He spent his childhood moving back and forth between foreign countries and different parts of the United States; almost immediately after his birth, his family moved to Arizona and then New Mexico for a short while. When he was three years old, they moved to the English town of Felixstowe, Suffolk. They subsequently moved to Virginia, followed by South Korea, where they settled in Seoul. When he was 10 years old, his family moved to Alabama. After graduating from Jefferson Davis High School in Montgomery, Alabama, he spent two years at New World School of the Arts of Miami Dade College. He was part of Group 29 of the Juilliard School's Drama Division (1996–2000), where he graduated with a Bachelor of Fine Arts.