Rotten Ralph
Voiced by: Hal Rayle (The Taming of the Ralph and Not-So-Rotten Ralph specials), Rick Jones (animated series)
- Alliterative Name: Both parts of his name begin with R.
- Amazing Technicolor Wildlife: He's a red cat.
- Cats Are Mean: What else would you expect from a feline who lives up to his moniker?
- Embarrassing Nickname: His owner Sarah sometimes calls him "pussykins" in the animated series, which embarrasses him and usually causes him to plead that Sarah not call him that.
- Everyone Has Standards: The animated series episode "One out of Nine Lives" shows that, as much as he hates his cousin Percy, he does not want him to die.
- Jerk with a Heart of Gold: He may be rotten, but he is a good cat deep down and he does care about his owner Sarah.
- The Prankster: He loves pulling pranks on others.
- Sapient Pet: He's a pet cat who behaves like a human being and is able to speak.
Sarah
Voiced by: Mae Whitman (The Taming of the Ralph and Not-So-Rotten Ralph specials), Brigid Tierney (animated series)
- Morality Pet: She is invariably shown to be the one person Ralph cares about the most.
Mom and Dad
Voiced by: Maggie Roswell (Mom, The Taming of the Ralph and Not-So-Rotten Ralph specials), Jennifer Sequin (Mom, animated series), Scott Meek (Dad, The Taming of the Ralph and Not-So-Rotten Ralph specials), Mark Camacho (Dad, animated series)
- Butt-Monkey: Both suffer a lot because of Ralph's antics.
- First-Name Ultimatum: Ralph's pranks often end in Dad yelling Ralph's name in anger.
- Unnamed Parent: Their first names are not known.
Percy
Voiced by: Corey Burton (Not-So-Rotten Ralph special), Daniel Brochu (animated series)
- Adaptational Jerkass: He was nothing more than Ralph's more well-behaved foil in the books, while the animated series and specials made his politeness less sincere by clearly showing him to relish getting Ralph into trouble and acting condescending towards his cousin for not being as well-mannered as he is.
- Early Installment Character-Design Difference: His debut in Rotten Ralph's Rotten Christmas depicts him as rather small and as a pretty generic cat. For his other appearances, he wears glasses as well as a bowtie and is closer to Ralph's height.
- Neat Freak: He cares little for untidiness.
Fleabag, Lulu and Bones
Voiced by: Will Ryan (Fleabag, The Taming of the Ralph special), Pat Musick (Lulu, The Taming of the Ralph special), Terrence Scammell (Fleabag and Bones, animated series), Sonja Ball (Lulu, animated series)
- Eyepatch of Power: Fleabag wears an eyepatch.
- The Smurfette Principle: Lulu is the only female of these three alley cats.
- Toxic Friend Influence: They are Ralph's friends and the animated series frequently has them encourage Ralph to do things that will get him in trouble.
