Tutter (born Tutter T. Tutter) is a blue mouse who lives in the Big Blue House with Bear on Bear in the Big Blue House. Tutter now lives in his mousehole, but for a time, he was raised by his Grandma Flutter, according to "The Big Little Visitor." Bear has baby pictures of him, so it's not known exactly when he moved into the Big Blue House.
Tutter knows a lot about cheese and enjoys eating it, talking about it and reading about it. Because of his small size, Tutter sometimes needs Bear to help him reach high places. This sometimes upsets Tutter, but he normally accepts this help with an endearing "Thank you, Bear."
Tutter has a large family. Besides his Grandma Flutter, who has taught him many things, he also has cousins, aunts and uncles (although his parents have never been seen nor mentioned). Many of his relatives are seen in "The Tutter Family Reunion." In the fourth season of the program, Tutter began attending Mouse School, taught by Miss Maxwell.
When Tutter is annoyed or upset about something, he will sometimes start shouting names of cheeses as if they were epithets. Another favorite saying of Tutter's is "Oh, hickory dickory!" (after the mouse who went up the clock.) One reason Tutter gets so upset is that he tends to focus a lot on cleaning and doing chores (a la Boober Fraggle). He likes to do these things perfectly and gets upset sometimes when they don't seem to be working out.
Tutter also has a tendency to worry and fret, another similarity to Boober Fraggle. He sometimes keeps his problems to himself, but generally finds that talking to his friends, or Bear, helps. Another characteristic of Tutter is that he has big dreams and thinks big about himself, but often finds himself at a loss when asked to describe what's unique or special about him.
Tutter is sometimes seen sleeping with a stuffed kitty.
- "Mouse Party" - Bear and the kids of the Big Blue House throw a birthday party for Tutter. Tutter performs the song "When I'm Older" expressing his hopes and dreams for the future. The events of this episode were later used for the stage-show "Bear in the Big Blue House Live: Surprise Party."
- "The Big Little Visitor" - Tutter prepares for a visit from his Grandma Flutter, but learns he doesn't have to go out of his way to impress her.
- "That Healing Feeling" - Tutter sprains his tail and fears having to visit Doc Hogg.
- "The Tutter Family Reunion" - Tutter's entire extended family comes over to the Big Blue House for their family reunion.
- "Step by Step" and "First Day at Mouse School" - Tutter prepares for going to school and then begins attending classes. Many other fourth season episodes also focus heavily on Tutter and his involvement in Mouse School.
- "The View from You" - Tutter struggles with a school project that requires him to share his point of view with his class.
- "Tutter's First Big Sleepover Bash" - Tutter holds his first sleepover at the Big Blue House, with Ojo and all of his classmates from Mouse School.