Peter Warren Hatcher - a boy who lives in New York City. At times, he feels neglected by his parents, mainly due to the amount of attention his brother's tantrums and disasters require. In the first book, he is nine years old and in the fourth grade, and in Double Fudge he is twelve and in seventh grade.
Farley Drexel "Fudge" Hatcher - Peter's brother, who is seven years younger. Disaster follows him everywhere he goes, often making a spectacle of himself and setting a bad image to his family. Some of his best-known stunts in the series include throwing temper tantrums, smearing mashed potatoes on the wall at a restaurant, scribbling all over Peter's transportation committee poster, and ultimately, swallowing Peter's pet turtle. When he decides to fly off a jungle gym, he jumps off, swallowing his front teeth by accident in the first book, and later he becomes obsessed with money.
Tamara Roxanne "Tootsie" Hatcher - Peter and Fudge's new baby sister, born in the second book. Fudge hates her in the beginning and attempts to exchange her for a two-wheeled bicycle. Later he hides her in a closet. Tootise is rather playful, curious and likeable. Her first word that she ever spoke was "Yuck," when she hears Peter say it. Then she says it as "Nu Yuck," when they decide to go back to New York City. She eventually learns more words, and likes to repeat what some people say. In the third book, she walks across Frank Fargo's paintings before they dry, leading Fargo to create a whole series of paintings featuring Tootsie's feet on canvas.
Anne Hatcher - mother of Peter, Fudge, and later, Tootsie. She is a housewife and then becomes a professional soccer player.
Warren Hatcher - father to Peter and Fudge and Tootsie. He is in the advertising business and he writes commercials. His agency has/had accounts with Juicy-O and the Toddle Bike company (for whom Fudge appears in a commercial), as well as a brief mention with X-Plode Cereal. In the first book, he dumps a bowl of cereal over Fudge's head when Fudge refuses to eat at the table like a normal person. In the second book, he takes a leave of absence from the ad agency to attempt to write a book. He also grows a beard in Superfudge, but later shaves it off in Fudge-a-Mania.
Turtle - Peter's pet dog, which he received after Fudge swallowed Dribble, for whom he was named. He is feared and hated by Sheila Tubman. It is unknown what breed of dog it is, though he is a large one. In the TV series, Turtle is a St. Bernard.
Uncle Feather - Fudge's new myna bird. They got it when Fudge wanted a bird for a pet in "Superfudge". His parents want him to get something else like a canary or parakeet, but Peter suggests a myna bird, much to everyone else's regret. Fudge wants one so he gets Uncle Feather, whose favorite thing to say is "Bonjour, stupid." In Double Fudge, Turtle likes to "sing" with him to Fudge's theme song about money.
Grandma Muriel - Anne's mother. She is known for using classic phrases and various tricks to help the kids. She originally was a gymnastics teacher. In the third book, she marries Sheila Tubman's grandfather, Buzzy Senior.
Cousin Howard "Howie" Hatcher - Warren's long-lost cousin, both of whom were great friends. Howie seems to have some slightly rude behavior, as he calls Warren "Tubby" even though he's lost some weight since, and a rather crazy driver when it comes to golf carts, and easily gets frustrated. Howie works as a park ranger in Hawaii and plans to move his family to the Everglades.
Cousin Eudora Hatcher - Howie's wife. Like her husband, she also calls Warren "Tubby." She is also pregnant, bur she isn't as rude as her husband, and is often the mediator between Howie and their daughters.
Flora and Fauna Hatcher - Howie's two identical twelve-year-old twin daughters. Nicknamed as the "Natural Beauties" and "Heavenly Hatchers," they are known for finishing each others' sentences and breaking into song in public, which really embarrasses Peter.
"Mini" Farley Drexel Hatcher - Flora and Fauna's little three-year-old brother. He acts similar to Fudge's 2-year-old-behavior in many ways.
Dribble - Peter's pet turtle, which he won at Jimmy Fargo's birthday party. Fudge sometimes played with him against Peter's will, and in the last chapter of "Tales of a Fourth Grade Nothing", he swallowed him whole.
Jimmy Fargo - Peter's best friend. He is mentioned as younger than Peter, though older than Sheila (assuming he's taller than her). Jimmy and his family originally lived a few buildings down from Peter and Sheila, and then moved into Peter and Sheila's building, before eventually moving down to SoHo.
Frank Fargo - Jimmy's father. He used to be an actor but became an abstract artist, judging from Peter's descriptions of some of his paintings. He also divorced his wife, which became very unsettling for Jimmy. Later, Tootsie accidentally walks across one of Frank's paintings, which inspires him for a new artwork series entitled "Baby Feet."
Anita Fargo - Jimmy's Fargo's mother and the first wife of Frank Fargo. She is first seen in the first Fudge book at Jimmy's birthday party giving Peter his pet turtle, Dribble. She later divorced Frank Fargo after an argument where she threw red paint at one of his paintings, to which Mr. Fargo took advantage of to display, calling the painting Anita's Anger. Jimmy said that his mother loves kissing, so she moved from New York to Vermont, where Jimmy and Peter believe people engage in much kissing there. Mrs. Fargo moved to a very rural community in Vermont, as Peter says at one point he is unable to contact Jimmy as he is visiting his mother in Vermont, and they had no telephone service there.
Sheila Tubman - Peter's archrival. She lives in Peter's apartment building on a different floor. Peter believes Sheila is a real know-it-all. She is Queen Of Cooties even though she is in 4th grade. She gives up cooties sometime between the fourth and seventh chapters. She is incredibly bossy and tries to run the report committee by herself. She has an older sister named Libby. In the second book, she exhibits a fear of dogs, especially Peter's dog, Turtle.
Libby Tubman - Sheila's older sister, who often is seen exercising in a leotard. Mrs. Hatcher hires Libby to help watch after Tootsie when the demands of a baby and other parenting responsibilities get to be too much for her to handle at once. Often annoyed by Sheila and her attention-getting, much like Peter is with Fudge, and is often willing to try to get along with Peter.
Jean and Bertram "Buzz" Tubman - Sheila and Libby's parents.
Buzzy Senior - Sheila's grandfather, who ends up marrying Muriel at the end of the third book.
Jake - Sheila's pet dog, whom she adores only because she isn't big and smelly. Peter doesn't learn about Jake until arriving at the cottage in Maine. Jake eventually befriends Turtle.
Henry Bevelheimer - The elevator operator, whom seems to know everybody in the apartment well. In Double Fudge, he helps out with Uncle Feather's brief period of being unable to talk, and is then later promoted to superintendent of the building and converts the elevator to self-service. In the TV series, Henry is the janitor and handyman of the building.
Ralph, Jennie and Sam - Fudge's original friends who live in the same apartment building. Ralph loves to eat and is very fat to the point where his own mother cannot lift him. Jennie is described by Peter as a mini-vampire since likes to bite people and is also quite rude, for she annoys Anne Hatcher and she even pees (or as she calls it,"making a tinkle") on the rug, and she dislikes it when she can't have it her way. Sam suffers nearly every phobia possible (though he gets over his one over parties) and also winds up getting chicken pox and having a new baby sibling.
Daniel Manheim - Fudge's new friend, introduced in Superfudge, as pudgy, Jewish, with a lot of red hair, and ears that stick out more than Peter's. Daniel is a bird expert, as seen in the beginning of Chapter 9 as he is lecturing Fudge on myna birds. He also delivers his tough-guy line: "Ya wanna make somethin' of it?" whenever asked of something. According to himself, he's six and lives at 432 Vine Street. He is also somewhat of a fussy eater; he constantly mentions that he does not like to eat onions, lima beans, peas and Oreos, and he also hates bread crusts and only drinks chocolate milk.
Mrs. Manheim - Daniel's mother, who is heavily concerned about her son and drives a red sports car.
Alex Santo - Peters new friend, introduced in Superfudge, as very small, with hair that hangs into his eyes, and is always wearing a T-shirt that says "Princeton, Class of '91". He is a Boy Scout and was away at Scout camp when Peter first moved to Princeton. He collects worms for Mrs. Muldour, an elderly neighbor.
Mrs. Muldour - One of Peter's new acquaintances. She is an elderly woman who lives near Peter also is to be believed that she eats worms as Peter and Alex dig them up for her.
Beverly Muldour - A pretty young woman Peter calls "Giraffe Neck" when he sees her at the art gallery and later seen as Mrs. Muldour's daughter. She eventually becomes Frank Fargo's second wife.
Joanne McFadden- A girl who sits behind Peter and becomes the object of his affection. She wipes his back off after Fudge pours ice down as Lois Lane is kissing Superman at the movies. They hold hands in the movies. When they stand under the misletoe hung in the classroom, she kisses Peter near his ear, and Peter does the same, except that she turns her head at the last second, with Peter ending up with a mouthful of hair.
Martha and Harvey- These are the only other of Peter's classmates in Princeton that aren't native to New Jersey. Martha wants to research her home state, Minnesota, instead of New Jersey, but Mr. Bogner decides to discuss it later. Harvey is from Pennsylvania.
Sharon and Elaine - Two other girls in Peter's class while he was in Princeton. Sharon is known for looking down at the ground or up at the sky; and Elaine is known for hitting guys her own age in the stomach. (Neither Sharon or Elaine's last names are revealed) They are friends with Joanne, and also socialize with Peter and Alex. Although Peter and Elaine are the same age, he was never socked in the stomach by her and they got along wonderfully.
Melissa Beth Miller - Fudge's new friend that moves into their apartment. She is Fudge's age and attends his special mixed group class at school. She has a cat named Fuzzball.
Richie Potter - Fudge's best friend from school. He is a rich boy with allergies, and likes to brag about his pee and poops. Fudge originally thought he was Harry Potter's cousin.
Mitzi - Friend of Fudge's whom he met on holiday in Maine. She is obsessed with Fudge. According to Fudge, she keeps monster spray and has a brother called Jacob. She is also the granddaughter of famous baseball player Big Apfel.
Mrs A - Mitzi's grandmother and Big Apfel's wife. She makes Mitzi's monster spray for her and makes really tasty cocoa. Peter and Fudge first meet her when they go round the neighbour's houses asking if the neighbours have seen Uncle Feather. Mrs A originally thinks Uncle Feather is Peter and Fudge's uncle. It is never mentioned if she is ever corrected.
Big Apfel - Famous baseball player who Peter is astounded to find is his new neighbour in Maine. Peter seriously looks forward to playing a game with him, but gets angry when he discovers that Big Apfel doesn't take the game seriously.
Olivia Osterman - The well-known, elderly neighbor to the Hatchers, she is almost 90 years old and used to be a Broadway actress. She doesn't understand why Peter named his dog "Turtle".
Mr. and Mrs. Yarby - The Juicy-O company president and wife, from Chicago - Warren's former employer. They stayed at the Hatchers' apartment at one point, which resulted in Fudge unknowingly causing trouble with them. This leads to the Yarbys becoming furious with the family and taking away Warren's Juicy-O account. Although Mrs. Hatcher is worried that Fudge cost her husband a big account, Mr. Hatcher is not concerned as Juicy-O had poor sales in stores.
Mr. George Vincent - The president of the Toddle Bike company. He chooses Fudge to star in the new commercial for his product, but gets furious when Fudge does not act on cue. Mr. Vincent is almost always seen smoking a big cigar.
Janet - Warren's beautiful secretary. She usually carries around a pocketbook with makeup items, Goldfish crackers and Oreo cookies. She kisses Peter for convincing Fudge to complete the commercial, but Peter secretly feels her kisses are too juicy.
Mr. Bogner- Peter and Alex's sixth-grade teacher. Peter is quick to learn that Mr. Bogner isn't dumb as some of his past teachers were.
Mr. Green - The moustached school principal. During an assembly with author Brian Tumkin illustrating a picture of a person Fudge knows, Fudge chooses Mr. Green.
Mrs. Hildebrandt - Fudge's first kindergarten teacher, who he calls "Rat Face" (with which Peter apparently doesn't disagree). According to Fudge, she is mean, wouldn't let him play with the round blocks, and wouldn't call him Fudge, so he had to kick her and climb on top of the cabinets. After he moves to the other kindergarten, Mrs. Hildebrandt frequently calls him Farley at every opportunity. When he leaves her kindergarten, she says to him "Goodbye, Farley Drexel", and when she meets Uncle Feather she says "What a beautiful bird Farley has". When Fudge tells her that Uncle Feather speaks French, Mrs. Hildebrandt says to him, "Parlez-vous Francais?" Uncle Feather replies, "Bonjour, stupid!" Fudge does not kick her in the TV series.
Ms. Ziff - Fudge's second kindergarten teacher. She is very nice and is reading "Arthur the Anteater" when Fudge arrives and he is impressed, since he is a fan of the book.
Brian Tumkin - A famous author that Fudge likes and gets to meet him at a school assembly.
Isobel - Librarian that Peter meets on holiday in Maine, and develops a serious crush on. Her nickname is Izzy. When Fudge asks Peter what's wrong, Peter admits that Isobel makes him feel dizzy. Fudge later tells that to Jimmy and Sheila. Jimmy doesn't share Peter's affection for Isobel, and Peter goes off her when she doesn't pick him for her team at the ball game. Isobel also persuades Fudge to write an autobiography of himself, entitled "Tell Me A Fudge", after he discovers his friend Mitzi has written a book about herself, "Tell Me A Mitzi".
Bicycle Bob - Bicycle repair salesman who acts as mentor to the children. When Peter accidentally swallows a fly, Bicycle Bob welcomes him to the ISAF club (I Swallowed a Fly) and recommends vanilla ice cream. According to Judy Blume, he is based on a real person.