Whenever he uses a figure of speech, he or his surroundings change to act on the pun (e.g. when he declares he is tired, he transforms into a tire; when he declares he is flat broke, he transforms into a flat disc and falls and shatters on the ground; on one occasion, in reference to his own power, he declares "This literal translation stuff slays me!" and giant letters reading "Literal Translation Stuff" fall from the sky to crush him).

It is Beetlejuice's power that affords him the (admittedly mostly self-declared) title of "The Ghost With The Most." Because of Beetlejuice's power, almost everyone in the Neitherworld is fair game for his pranks, but no more so than himself, since even he is not immune to careless use of his power; for example, he was tricked by his enemies into declaring "I'm coming apart at the seams!" which caused him to break into several pieces, with which his enemies then absconded, rendering him nearly helpless until, with Lydia's help, he reassembled himself. Sometimes Beetlejuice will mix up one of his transformations (like when Lydia told him to turn into a stake to fight off Count Mein, he turned into a flank steak). One limit to Beetlejuice's abilities is that his body must be fully assembled to work his magic; for example, when his head was taken away by a tribe of island ghosts to be eaten, it was helpless to fight back without the rest of his body.

At the same time, various body parts (including his feet and his entire torso) occasionally developed minds of their own, independent of Beetlejuice's control. His fears (sandworms, cleanliness) can also hinder his abilities. Beetlejuice's main pastime is pulling various pranks on the other denizens of the Neitherworld, and coming up with get-rich-quick con schemes to get money, as he dreads having to get a job. His favorite foods are insects of various types, especially beetles. He loves causing mayhem in the Neitherworld, being filthy, and scaring people in the real world, such as Lydia's parents.

The things he hates include sandworms, cleanliness, and anything "cute". He expresses his likes and dislikes via variations on a single catchphrase ala such examples as "Nerd humor...you know I love it!" or "Sandtraps...you know I hate 'em!" BJ repeatedly claims to have died centuries before, though his references often happened hundreds of years apart.

In addition his parents are in the Neitherworld as is his childhood home and there are photos of him when he was a baby. He had the same complexion, tongue and personality.

Lydia Deetz - A goth girl in her preteens/early teens, an amateur photographer, entomologist, seamstress and sketch artist, but who doesn't feel like she fits into the real world. In the series, Lydia attends "Miss Sharon's School for Girls" and is in seventh grade. In the events of the pilot episode, Critter Sitters, they had already known each other for a year as they are celebrating their first anniversary of friendship; Lydia is Beetlejuice's best friend. Beetlejuice frequently addresses her as "Lyds" or "Babes" rather than "Lydia" though he has from time to time. Lydia knows full well how to summon Beetlejuice to her presence, or makes her own way to his, all by chanting his name outloud three times; occasionally she is shown making use of a longer, more elaborate ritual to bring him out of the Neitherworld or send herself into it. Unlike Beetlejuice himself, Lydia is almost universally beloved by the Netherworld cast of the show.

In the pilot episode, "Critter Sitters," she is shown summoning him through the longer ritual; as part of the ritual, she willfully changes the color of her clothing. She is not the only person capable of summoning Beetlejuice (in one episode, Claire Brewster summons him accidentally), but she is the only person he will actually obey.

Lydia looks up to him in certain ways, admiring his outrageous sense of humor and dedicated non-conformity, though in other respects she sometimes has to virtually parent him. In one episode it is made clear that Beetlejuice's dedication to her is a source of Lydia's own self-confidence.

Meanwhile, those who conceivably threaten their relationship (e.g. Prince Vince) are the objects of his profound jealousy and resentment. In one episode, we learn that Beetlejuice actually has a working shrine to her in his mind.[citation needed] Lydia never shows any romantic interest in anyone else except Prince Vince and that quickly turned into a straight out friendship. She's kissed Beetlejuice a few times, and gone on several dates with him. Also when inside Beetlejuice's head she gave several dollars towards the maintenance of his shrine to her. Her main hobbies are photographing every sort of strange things, hanging out with Beetlejuice, drawing and watching horror movies. She has shown that she is extremely gifted with anything mechanic and understands a lot about cars (she knew what to do to build Doomie, while Beetlejuice did not know a few things like what was a carburetor).

Jacques LaLean - A Francophone skeleton-bodybuilder, based upon the fitness guru Jack LaLanne, and neighbor of Beetlejuice. A running gag in the series entails Jacques getting broken down into multiple pieces, often thanks to Beetlejuice. In spite of the poltergeist's antics, Jacques actually likes him, and in one episode it is revealed that Beetlejuice likes Jacques despite his pretensions to the contrary.

Ginger - A (not very good) tap-dancing spider, named after Ginger Rogers. Another of Beetlejuice's neighbors, her act is often ruined by a prank of Beetlejuice. She often has dreams of being famous and can be sensitive to cruel pranks.

Prince Vince - The ruler of the Neitherworld. He looks and acts almost identically to Tim Burton's "Vincent", who was the star character in one of Burton's early animation shorts (see Vincent (film)). Both also bear a resemblance to Johnny Depp, which may have been a sight gag, since Winona Ryder (who played Lydia in the film), was Depp's longtime girlfriend. Mopey and depressed (the weather turns gloomy and rainy in response to his mood), Prince Vince cheers up when he meets Lydia and they begin informally dating, but the relationship cools to a friendship when he asks her to be his Princess and she politely declines, being barely a teenager.

The Monster Across the Street - A tall, hairy monster from the West, who bears a slight resemblance to Gossamer from the Warner Brothers animation studio, and is another neighbor of Beetlejuice. He can't stand Beetlejuice, but refers to Lydia politely as "Miss Lydia." He speaks with a southern twang.

Poopsie - The Monster's dog, one of Beetlejuice's favorite prank victims.

Scuzzo the Clown - Beetlejuice's cackling rival in prank-playing and whatever other endeavor Beetlejuice might be pursuing in a given episode. He is considered a comedy genius in the Neitherworld's version of France, although this was only revealed years after his first appearance and thus should not be taken as evidence that he was created as a direct parody of Jerry Lewis.

Fuzzo the Clown - Scuzzo's brother.

Dragster of Doom (nicknamed Doomie) - Beetlejuice's sentient car. Doomie is normally quite sensitive, but due to the abnormal brain Beetlejuice gave him during his construction, Doomie turns into a vicious "four wheeled werewolf" type of monster when angry or startled, much like Jekyll and Hyde. Incidentally, even in his more sedate form, he displays subtle dog-like traits such as panting. Implying that he fills more of a pet-like role than that of a vehicle to Lydia and Beetlejuice. A reoccurring gag is when Doomie often turns into his "Werewolf stage" to chase Dogs.

Captain Kidder - A pirate/headhunter who tells jokes which are not applauded. His name is a reference to the phrase 'to kid' which means, to tell a joke.

Flubbo - A slug-like bespectacled ghost with multiple arms.

Judge Mental - A skeletal judge. His name is a play on the word judgmental.

Mayor Maynot - The mayor of the Neitherworld, completely redesigned in the second season from a stereotypical old time mayor to a more modern day mayor. The mayor hates Beetlejuice and would love nothing more than to feed him to the sandworms. Though at first glance he looks like a mummy it was revealed in some episodes that he is actually an Invisible Man. His name is a play on "May Or May Not".

Armhold Musclehugger - A bodybuilder ghost based on Arnold Schwarzenegger who's Mr. Neitherworld and the fitness king. He is Jacques' prime arch-rival.

Chester Slime - A lawyer.

Germs Pondscum - A secret agent with "a license to prank," based on James Bond.

Mr. Monitor - Co-president of the Nutwork which airs broadcasts of Beetlejuice's adventures; his head consists of several TV screens.

The Monstress Across the Street - The Monster's girlfriend.

Poopette - The Monstress' dog.

Mr. & Mrs. Juice - Nat and Bea ("gnat" and "bee," two types of insects), Beetlejuice's parents. Unlike Beetlejuice, they are very neat and clean and always insist that Beetlejuice bathes, cleans his room, and gets a job. Beetlejuice is terrified of them for these reasons.

Uncle Sid - Beetlejuice's uncle, who thinks Lydia is his nephew's girlfriend. He loves telling horrible jokes. Interestingly, there's a human in the living world that resembles him and tells bad jokes as well.

Donny Juice - Beetlejuice's little brother. However, other than the family resemblance, Donny is as different as can be from his older brother Beetlejuice. Everyone in the Netherworld prefers him to his brother. He is clean, tidy, and generous, but, rather insecure. His main problem is that he is a little too kind (in the vein of Mr. Rogers, Pat Boone, or Ned Flanders). No explanation is offered for why his name breaks the bug-oriented naming pattern in the Juice family, although it is almost certainly a direct parody of Donny Osmond.

Bartholomew Batt - An old cartoon character, a parody of Mickey Mouse and Felix the Cat.

Little Miss Warden - Warden of the sickeningly sweet Neitherneitherland, a parody of Shirley Temple and, to a smaller extent, Tinker Bell.

Jesse Germs - A skeletal outlaw based on Jesse James and Clint Eastwood.

Mrs. Bugsley - The mayor's secretary, who has a shrunken head, in one episode he received an award from "The Socitey of People Who Hate Hats".

Lip Scum - An annoying character, he is basically a giant mouth with eyes, arms, and legs. He is the only creature in the Netherworld everyone considers even MORE annoying than Beetlejuice.

Dr. Zigmund Void - A large-headed psychiatrist based on Sigmund Freud.

Bully the Crud - A Neitherworld-based outlaw based on Billy the Kid, who appears in the episode "Pest o' the West." He develops a crush on Lydia and tries to force her to marry him.

Barry Me Not - A Neitherworld TV personality who appears in various "commercials" that sometimes pop up to emphasize a particular plot point in a humorous aside. Unlike the rest of the show, Barry Me Not's vignettes are computer-generated animation. He almost never interacts with the rest of the characters.

Goody Two Shoes - A fairy from the Nietherworld's Bereua of Sweetness and Kindness, and perhaps the only being more powerful than Beetlejuice, as all of Beetlejuice's tricks proved useless on her. She is able to transform anyone into a sweet and clean version of themselves. She is somewhat like little miss warden except that Miss Warden does her job to reform while Goody does her job as kind of a sport, and hates it when folks get along.

Napoleon Bonesapart and Marie Marionette - A headless skeleton and a headless zombie based on the French general Napoleon Bonapart, and Queen Marie Antoinette.