Mr. Stewart is a character from the anime series Sonic X, he is a government agent who is disguised as a teacher to keep an eye on Sonic and co. by the President.
He teaches Chris Thorndyke and his classmates, such as Danny, Frances, and Helen. He always looks out for the kids in his class. He is also a fan of Chris' film actress mother, Lindsey Flair.
Mr. Stewart is voiced by Andrew Rannells in English, and by Michio Nakao in Japanese.