Humans •
Ozzie – The beloved guardian of Earl, a 30-something bachelor •
Millie – The doting guardian of Mooch, married to Frank •
Frank – The cantankerous and sometimes reluctant caretaker of Mooch, married to Millie •
Butchie – Owner of Fatty Snax Deli, who tries to stop Mooch and Earl from eating his food. Formerly a butcher, Butchie became a vegan in June 2020, and re-opened his deli with a vegan menu. •
Doozy – The chipper and youthful friend to all animals, but especially fond of Guard Dog •
Bushy – Doozy's best friend and a hero to Tom-Tom •
Ms. Lulu – The pet psychic • '''Sourpuss's Owner''' – Sourpuss's owner and a friend of Millie's
Animals •
Bip and Bop – Two nutty squirrels who like bonking ground-dwellers in the head with nuts (described as antagonists of the strip) •
Crabby – An unhappy crab who speaks with frequent "salty" language (denoted by stars and typographical symbols); he claims to have gone on many adventures, such as on a pirate ship, inside a whale, and even meeting the
Popeye cast •
Sparky (formerly
Guard Dog) – A tough-looking, tethered dog with a soft heart. Sparky's mission is to remind humans that it's wrong to perpetually chain a dog. He was finally untethered in a November-December 2023 storyline after being abandoned by his previous owner and saved by Earl, Mooch, Ozzie, Doozy and her mother. Doozy adopted Guard Dog who was renamed Sparky, McDonnell's homage to
Charles M. Schulz. •
King Crab – The crabbiest of them all, ruler of all he sees (since he is at the bottom of the ocean, however, he cannot see anything) •
Lollipop – Crabby's soft-shell wife •
McGarry – A bird who lives at the shore and tries to convince Crabby not to swear •
Mussels Marinara – A mussel that's always talking about its muscles, Crabby's buddy •
Noodles – A street-smart alley cat with a heart of gold, and friend and mentor of Shtinky's •
Philippe – A bird always wooing his love, Phoebe •
Shnelly – The house cat for whose love Mooch and Noodles fight; only the tip of her ears are seen through her owner's window •
Shtinky Puddin' (A.K.A.
Jules) – A little kitten with a short memory and formerly the pet of a very wealthy human companion, he wants to save the world and often speaks out about
animal rights, especially saving the tigers •
Sid – A fish who lives in a goldfish bowl in Mooch's house, and wishes to be free •
Little Earl (a.k.a. "Speed-o") – Mooch's pet snail obsessed with "walking" Mooch •
Sourpuss – A cranky cat who hates Mondays and can usually be found hiding under the couch or standing on the porch of his house, complaining •
Woofie – The big, happy, energetic dog that "wuvs" everything and everyone, especially Mooch, who does not appreciate the "wuv" •
Chippy and Monk – Two chipmunks, who are sarcastic and spunky members of the Mutts book club •
Lamont – A groundhog, featured in Groundhog Day strips •
Moe – A mole, stand-in for Lamont; he does not work Sundays •
Robert – A bird, friend of Earl and Mooch •
Wuzzy – A bear who Mooch tries to hibernate with in the winter •
Loretta – A squirrel who is the "wife" of Bip and Bop •
Shmousie – A mouse who Mooch (and sometimes Earl) try to get out of his hole so they can catch him ==Recurring storylines==