"By the Book" is the second segment of the twentieth episode of Star vs. the Forces of Evil. It premiered on September 12, 2016 alongside "Goblin Dogs", and is the second segment of the seventh episode in the second season.
After an argument with Star, Glossaryk goes into hiding in a donut box. While Star and Marco try to convince him to come out of hiding, Ludo plots to capture Star.
- Eden Sher as Star Butterfly
- Alan Tudyk as Ludo
- Adam McArthur as Marco Diaz
- Jeffrey Tambor as Glossaryck
- October 6, 2016 (United Kingdom and Ireland)
- November 15, 2016 (Italy)
- December 18, 2016 (Japan)
- December 22, 2016 (Latin America)
- January 10, 2017 (Poland)
- January 13, 2017 (Southeast Asia)