"Mayor for a Day" is the first segment of the fifty-first episode of Big Hero 6: The Series. It premiered on September 28, 2020 alongside "The Dog Craze of Summer", and is the first segment of the second episode in the third season.
- Ryan Potter as Hiro Hamada
- Scott Adsit as Baymax
- Génesis Rodríguez as Honey Lemon
- Khary Payton as Wasabi
- Jamie Chung as Go Go Tomago
- Brooks Wheelan as Fred
- Jane Lynch as Supersonic Sue
- Tim Simons as Supersonic Stu
- Sean Giambrone as Richardson Mole
- Diedrich Bader as Bluff Dunder
- Jeanne Sakata as Mayor Saito
- Zehra Fazal as Basemax
- John Michael Higgins as Mini-Max
- This is the first episode to introduce the new 11-minute segments format.
- While Richardson Mole as acted antagonistic towards Big Hero 6, this is the first time where he actively becomes a villain to face off with them.
- Supersonic Sue still does not realize that Boss Awesome has retired.
- This is the first appearance of the Mayor of San Fransokyo.
- Fred states that he is a fifth generational Frederickson. Based on this comment, it can be stated that his great-great grandfather was the only one not named Frederick.