Nice Mice

"I cannot imagine mice as the embodiment of evil. Mice are such charming little creatures, and it is not by accident that Mickey Mouse became an absolutely universal hero."

—Andrey Konchalovskiy on why he changed the Mouse King to the Rat King in his adaptation of The Nutcracker

Unlike rats, mice are often portrayed as nice and heroic even though they are common household pests.

Being very small and cute, yet traditionally wild, the mouse is an animal often used as a metaphor for someone easily underestimated. Thus, mouse characters and humanoid mouse races tent to be heroic and really good people, yet easily underestimated. In many works, this last trait is something they have grown to deeply resent. It's hard to demand respect from someone when you can't even reach his knees and your voice is very squeaky - no matter how brave you are.

These mice characters designed to be likable one way or another. Some are heroic, some are nice, and some are both.

Contrast You Dirty Rat for rodents, specifically rats, who are portrayed as disgusting and maybe carriers of literal or metaphorical disease.

Examples of Nice Mice include:

Commercials

Chuck E Cheese

Comic Books

In Art Spiegelman's Maus, a narrative of the author's father's struggle to survive the Holocaust, the Jews are drawn as mice. Nazis are drawn as cats, and the Allied troops (particularly Americans) are drawn as dogs.

Film -- Animated

The mice in Cinderella are not just nice, they are ultimately responsible for helping Cinderella's dream come true.
Roquefort from The Aristocats
The mice in The Rescuers and The Rescuers Down Under are nice.
Same with most of the mice from The Great Mouse Detective. The villain, Ratigan, was definitely a mouse in the books, however. But this is somewhat more dubious in the movie, though he vehemently denies being a rat.
- Basil may not be nice, but he's still good.
Fievel and the mice from the An American Tail movies are all nice. They're also stand-ins for poor oppressed minorities in the human world.
- The villains from the third movie are also mice, however.

Film -- Live Action

Mousehunt's mouse counts, but it's a more blurred example due to Alternate Character Interpretation. Obviously the audience is supposed to feel sorry for him, being hunted so ruthlessly by two humans, but he outsmarts them so often that it's clear he's not an ordinary mouse. So, if he's capable of understanding that, perhaps he's capable of understanding what a nuisance he is to two humans who consider the house their property.

Literature

The mouse in Aesop's fable The Lion and the Mouse makes this trope Older Than Feudalism.
In The Chronicles of Narnia, mice is the most Badass race, and the only race that gets a racial storyline of its own. All other races of talking animals are given speech as a divine gift at the dawn of time. The mice, however, are so small and insignificant that they are overlooked by Aslan himself. However...
- Moving on to The Lion, the Witch and the Wardrobe, the mice earn their rank among the ascended animals by making a heroic attempt at Save Your Deity.
  - In that story, mice chew off the ropes that bind The body of Aslan. As a result, mice are promoted to that rank of talking animal, and many years latter the mice are considered among the most bravest and honorable of all the animals. The chief of the mice, Reepicheep features in Prince Caspian and Voyage of the Dawn Treader as one of the main heroes of the books.
- In Prince Caspian the mouse militia fearlessly go up against far larger enemies, routinely taking them out by being ignored in the fray and chopping them from underneath. Culminating in the Heroic Sacrifice of their commander Reepicheep and his army's quite special way of dealing with that situation.
- In Voyage of the Dawn Treader, Reepicheep is one of the main charactes, and arguably the bravest of them all. Lucy works quite hard to resist her urge of cuddling him, since she understand that such behavior from her would hurt his pride. The local Jerkass human taunts him for his size, but he quickly teaches the far larger human to fear him. Also, while the other heroes just happen to be on that journey for miscellaneous reasons, Reepicheep is the one doing the journey as a holy quest.
In The Hitchhikers Guide to The Galaxy, mice are revealed to be highly intelligent pan-dimensional beings; the little furry squeaky things we see are just their avatars in this dimension. Millions of years ago, they built the super Computer Deep Thought as a means of discovering the Answer to the Great Question of Life, the Universe, and Everything. They succeeded.
Redwall uses this a lot.
Despereaux and the other mice in The Tale of Despereaux (rats are bad, except for Chiarascuro, who is good)
In The Wonderful Wizard of Oz fieldmice rescue Dorothy, Lion, and Toto from the poppy field by dragging them away. (In the film The Wizard of Oz Glinda makes it snow to rescue them.)
Subverted in Moving Pictures with Definitely Not Squeak, a mouse who began talking under the influence of Holy Wood cinemagic. Told of this trope, he was outraged that humans consider his kind sweet and delicate, as he was the most Badass mouse in the house and proud of it.

Video Games

Video game: Pipsy Mouse from Diddy Kong Racing.
In Pokémon, Plusle and Minun are always there to cheer their trainer and the other Pokemon in the party on (and cry when they lose)
- Pikachu is somewhat of a subversion in that it can be moody, but otherwise plays the trope straight (Ash's Pikachu in particular.)

Western Animation

Pinky and The Brain: Pinky is nice, if completely cracked. The Brain—not so much, but he's a Jerk with a Heart of Gold.
Tom and Jerry: a lot of Jerry's nastiness is in provoked self-defense from Tom, but some of it is just tormenting Tom for the hell of it. When it comes to other animals, though, Jerry is pretty universally nice. He's nice to canaries, baby woodpeckers, baby ducks, baby seals, escaped lions, circus Elephants (on more than one occasion even).
Surprisingly subverted (considering it's a '30s cartoon) in the Fleischer short Fresh Vegetable Mystery where the mice are the bad guys.
Mickey Mouse and Minnie Mouse: Both are nice. Hands down.
- Subverted with Mortimer Mouse though.
Hanna-Barbera: Dixie and Pixie were usually only acting in defense from Mr. Jinks, and only did the stealing of the cheese to survive, if memory serves.
- Sometimes it would switch around where Jinks was the hero of the episode and Pixie and Dixie would get there Comeuppance in the end.
Looney Tunes: Speedy Gonzales is a mouse who pretty much only steals cheese to help his compadres. Sniffles is well-meaning, if annoying.
The mice from Capitol Critters were nice.
Biker Mice From Mars is about Badass Biker mice who protect Earth from evil.
Rastamouse. Irie, man.
Massively subverted in The Simpsons' Itchy the mouse, who is a cheerful murderous psycho.