Grandma Flutter is Tutter's grandmother. She's a blue mouse with gray hair piled on her head.
She was first mentioned in "What's in the Mail, Today?" during the song "Dear Grandma." She appeared on the series in person in "The Big Little Visitor" and in several later episodes. She was also mentioned by Tutter in the episode "When You've Got to Go!"
Grandma Flutter dotes on her grandson, and he loves her just as much. Grandma Flutter is known for liking things to be clean, but she's also been a cha-cha-cha champion, and has her own song, "The Grandma Mambo." She is a trained dance instructor with the Ha-Cha-Cha Dancing Academy and teaches everyone in the Big Blue House to dance to it in "You Learn Something New Every Day." She raised Tutter for an unspecified period of time before he moved into the Big Blue House. Viewers learn even more about some of Grandma Flutter's many and varied life experiences in "Grandma Flutter's 100th Birthday."