The comic strip originally revolved around Dilbert and his "pet" dog Dogbert in their home. Many plots revolved around Dilbert's engineer nature or his bizarre inventions. Also prominent were plots based on Dogbert's megalomaniacal (evil) ambitions. Later, the location of most of the action moved to Dilbert's workplace at a large technology company, and the strip started to satirize technology, workplace, and company issues. The comic strip's popular success is attributable to its workplace setting and themes, which are familiar to a large and appreciative audience; Adams said that switching the setting from Dilbert's home to his office was "when the strip really started to take off."

Dilbert portrays corporate culture as a Kafkaesque world of bureaucracy for its own sake and office politics that stand in the way of productivity, where employees' skills and efforts are not rewarded, and busy work is praised. Much of the humor emerges as the audience sees the characters making obviously ridiculous decisions that are natural reactions to mismanagement.

Dilbert

The main character in the strip, Dilbert is a stereotypical technically-minded single male. He is usually pictured wearing a white dress shirt, black trousers and a red-and-black striped tie which inexplicably curves upward (though it flattens when he meets Antina, an extra-masculine female co-worker; Adams has said that the phallic symbolism was intentional in Seven Years of Highly Defective People. Adams has also claimed that it might be a metaphor for Dilbert's inability to control his environment). In old Dilbert strips, his neck was long shaped. Over time, his neck has become smaller. Dilbert received his Masters degree in electrical engineering from MIT; he understands engineering well and has good ideas, but has a poor social life. Neither attractive nor blessed with tremendous social graces, Dilbert is capable but ignored at work, and struggles with his romantic life. While he is frequently seen having dates with eligible women, his dates almost invariably end in disaster, usually in surreal and bizarre ways. Dilbert loves computers and technology and will spend much of his free time playing with such things. Two comic strips show the tie pointed downward, which, according to Adams, was a secret message to readers of his newsletter that Dilbert had "lost his innocence" with his girlfriend, Liz.

Pointy-haired boss

The manager of Dilbert and the other engineers, and the main antagonist of the strip; his real name is never mentioned. In earlier strips the Boss was depicted as a stereotypical late-middle-aged balding middle manager; it was not until later that he developed his signature "pointy hair". He is hopelessly incompetent at management and is very bombastic. He does not understand technical issues but always tries to disguise this, usually by using buzzwords he also does not understand. The Boss treats his employees alternately with disdain or neglect; he is narcissistic, using them to his own ends regardless of the consequences to them. Adams himself wrote that "He's not sadistic, just uncaring." The Boss's level of intelligence varies from near-vegetative to perceptive and clever, depending on the strip's comic needs. His utter lack of ethics, however, is perfectly consistent. His brother is a demon named Phil, the Prince of Insufficient Light, and according to Adams the pointy hair is intended to remind one of devil's horns.

Wally

One of the oldest engineers. Originally was a worker trying to get fired to get a severance package. He hates work and avoids it whenever he can. He often carries a cup of coffee, calmly sipping from it even in the midst of chaos or office-shaking revelations. Wally is extremely cynical. He is even more socially inept than Dilbert, and references to his lack of personal hygiene are not uncommon. Like the Pointy-Haired Boss, Wally is utterly lacking in ethics and will take advantage of any situation to maximize his personal gain while doing the least possible amount of honest work. Squat and balding, Wally is almost invariably portrayed wearing a short sleeved dress shirt and tie. Adams has stated that Wally was based on a Pacific Bell coworker of his who was interested in a generous employee buy-out program -- for the company's worst employees. This had the effect of causing this man -- whom Adams describes as "one of the more brilliant people I've met" -- to work hard at being incompetent, rude, and generally poor at his job to qualify for the buy-out program. Adams has said that this inspired the basic laziness and amorality of Wally's character. Despite these personality traits Wally is accepted as part of Dilbert, Alice and Asok's clique. Although his relationship with Alice is often antagonistic and Dilbert occasionally denies being his friend, their actions show at least a certain acceptance of him.

Alice

One of the more competent engineers. Alice has a huge, triangular hairstyle. She is often frustrated at her work not getting proper recognition, which she believes is due to her sex. She also has a short, often violent temper, sometimes putting her "Fist of Death" to use, even against the Pointy Haired Boss. Alice originally depicted a series of female characters, like Ted the Generic guy, and appeared for a time as the current Alice with a somewhat more normal hair style before, like the Boss, she finally developed her signature triangular hair. Alice is claimed to be based upon a woman that Scott Adams worked with named Anita, who is described as sharing Alice's "pink suit, fluffy hair, technical proficiency, coffee obsession and take-no-crap attitude."

Dogbert

Dilbert's pet dog (if such a subordinate appellation can be applied to him). Dogbert is a megalomaniac intellectual, planning to one day conquer the world. He once succeeded, but became bored of the ensuing peace and quiet. Often seen in high ranking consultant jobs, he constantly abuses his power and fools the management of Dilbert's company, though considering the intelligence of the company's management in general and Dilbert's boss in particular, this is not very hard to do. Dogbert also enjoys pulling scams on unsuspecting, and usually dull customers to steal their money. However, despite Dogbert's cynical exterior, he has been known to pull his master out of some tight jams. Dogbert's nature as a pet was more emphasized during the earlier years of the strip; as the strip progressed, references to his acting like a dog became less common, although he still wags his tail when he perpetrates his scams. When an older Dilbert arrives while time-traveling from the future, he refers to Dogbert as "majesty", indicating that Dogbert will one day indeed rule the world...again, and make worshiping him retroactive so he could boss around time travelers.

Asok

Pronounced "Ah-SHOKE" A young intern. He works very hard but does not always get proper recognition. Asok is intensely intelligent but naive about corporate life; the shattering of his optimistic illusions are frequent comic fodder. Asok is Indian, and has graduated from the Indian Institute of Technology (IIT). The others, especially the Boss, often unwittingly trample on his cultural beliefs. If Asok mentions this, he is normally ignored. Asok's test scores (a perfect 1600 on the old SAT) and the fact his IQ is 240, show that he is the smartest member of the engineering team. There are a few jokes about him having psychic powers which he learned at the IIT. (Examples are: telekinesis; being able to move objects with ones mind, etc.) Yet despite his intelligence, ethics and mystical powers, Asok sometimes takes advice from Wally in the arts of shiftlessness and passing-the-buck, and Dilbert in surviving the office bureaucracy. He died while test piloting the company's prototype moon shuttle. Dilbert cloned his body, but because Carol put candy in his DNA jar, he is part Snickers bar. By random luck (which Dilbert was hoping for), Asok's soul reincarnated into his new body. Luckily, his studies of Guided Reincarnation and Advanced Shapeshifting at IIT allowed him to assume his usual form.

Carol

The misanthropic and bitter secretary of the Pointy-Haired Boss, who hates her boss and all of her co-workers. Originally a minor character in the company where Dilbert, Alice, Asok, and Wally work, her character's popularity as the "secretary from hell" grew enough to the point where she was given entire storylines to herself in the strip. The Boss has made it clear that Carol will never be promoted past secretary even though she has an MBA.

Ratbert

A rat formerly used as a laboratory test animal. A cheerful pollyanna character, and something of a nitwit though he does make the occasional brilliant observation. He usually gets all the lowest and most menial jobs (e.g. temp). Ratbert is originally disliked by Dilbert for being a rat, but is later accepted as a member of the family. He was not originally intended as a regular character, but because of his popularity with readers he was kept.

Catbert

The company's evil feline Human Resources director. Although he was originally just supposed to be around for a few strips, the fans named him and demanded more of him. He derives sadistic pleasure from seeing employees worry about their jobs, and particularly enjoys tormenting Wally. Merely mentioning the term "layoffs" causes him to purr with delight. Unlike Dogbert, Catbert has no apparent owner, but retains all of the qualities of a cat, and frequently purrs or sheds or performs other acts of "catness". He is particularly cooperative and friendly with the Pointy Haired Boss.

Dilmom

She is homely and intelligent. She used to think Dilbert worked at a railroad because he is an engineer. She's often selfish and openly uncaring towards her son; in the TV series she states that, although she loved him, she did not actually like him. She has nearly the same level of technical knowledge as Dilbert, although she has him do technical work for her. She is obsessed with Scrabble, and has been accused of cheating with "counterfeit vowels". (This is a reference to Scott Adams' own mother.) She also is on an unnamed department store's "bad customer list", because she returned over a thousand items to the store, one scarf in particular 17 times.

Phil the Prince of Insufficient Light

A minor demon who punishes people for small crimes by "darning them to heck" with his "pitchspoon", a parody of Satan (the "Prince of Darkness"). Such crimes include using copier paper for the printer, stealing a chair from another cubicle, finishing off the last coffee from the coffee maker without topping it up. As a minor demon Phil's punishments tend to be of an annoying rather than downright tormenting nature, such as being forced to sit at a secretary's desk and be teased by coworkers or being forced to sit among the accountants at lunchtime and listen to their inherently boring conversations. Ostensibly, Phil is eventually revealed to be the Pointy-Haired Boss's brother. Adams is inconsistent with his depictions of Phil; he sometimes has horns and sometimes does not, and sometimes carries a pitchfork rather than a spoon. Adams has stated that the inconsistency is because he sometimes forgets that Phil is not supposed to have a cape or a pitchfork.

Bob the Dinosaur

A vegetarian dinosaur who is the wedgie enforcer at the office. He was found after Dilbert calculated that dinosaurs could not be extinct, and they therefore must be in hiding. Bob is found hidden behind the couch. Bob has a wife (Dawn) and son (Rex), who also live in Dilbert's house, but they are seen far less frequently than he is, since most of his time is spent at Dilbert's office, where his wedgie duty is constantly needed while working with incompetent co-workers, salesmen, or clients. He has also revealed that being a dinosaur he is, of course, a COBOL programmer.

Garbageman

Dilbert's garbageman is a mysterious philosopher and scientist. He occasionally solves extremely complex problems for Dilbert and has several inventions, including a weather control device, a phaser, and an anti-stupidity gun. He also goes through Dilbert's trash on occasion, and once completed a robot that Dilbert had thrown out. In the TV show, it is revealed that he is the only garbageman for the whole city, and is able to collect for all houses through teleportation.

Tina

Tina was introduced as a technical writer in order to add more females to the cast. She feels that her skills are unappreciated. Initially, she was called "brittle" and would believe every statement was intended to be sexist in some way. Readers criticized Adams for what they believed to be a stereotypical and negative portrayal of women. In response, Adams created the character Antina (the antidote to Tina), who was very smart and did not look like a typical woman. Readers criticized him again for Antina, believing that he was making fun of lesbians.

Ted the Generic Guy

Ted is the name that creator Scott Adams attributes to a number of one-shot characters, because they all look the same. He has gone by other aliases in the strip. When Adams needs to kill or fire a co-worker, he often kills Ted.

Elbonians

People from a fictional Fourth World nation, used as a parody of outsourcing. Their culture is radically different from Western culture, and their patriarchy often annoys Alice. Their country is covered in waist-deep mud which they keep wet using expensive bottled water as revealed in one strip. The main vehicle of their national airline is essentially a giant slingshot. At one point, the French declare war on Elbonia because they tried to launch a French satellite with the town slingshot before Dilbert can intercede; the satellite flattens the French Embassy. At another time Dogbert lobbies Switzerland to "liberate" Elbonia's oil. Elbonia was first described as an Eastern European nation. Elbonia's traditional hats, long beards, male-centric culture and technological backwardness suggest it is modeled after a Third World Islamic society, such as Afghanistan; it is also similar to Post-Soviet States in its headwear and former communism. Scott Adams stated in Seven Years of Highly Defective People that Elbonia was created to allow for a foreign nation inoffensive to people outside the United States, and is based on the average American's perception of any country without cable TV. Despite this, Adams has been accused of racism several times.

Accounting trolls

Sadistic trolls from the accounting department whose bodies are 95% saliva. As Dogbert shows, their brains are so hard-wired that seeing someone wearing a baseball cap backwards causes their heads to explode, which he referred to as a "paradigm shifting without a clutch." The trolls' accounting offices resemble a cavernous Hell. They were originally ruled by a witch who turned Dilbert into an accounting troll but was destroyed when Dilbert, assigned to budget erasing, erased the accounting department's budget.

The trolls are rarely given names, however occasionally a troll by the name Nordlaw is referenced. The first troll met in the comics was named Bradley. In the television series one of the trolls was voiced by Gilbert Gottfried.

Loud Howard

Another coworker who became a regular character in the TV series, despite appearing in just a few comic strips (on 21 April 1995  and 17 March 2006 , and again by popular request on 11 October 2006 ).

Loud Howard is incapable of speaking quietly, and in the TV series his overpowering voice often breaks anything and everything around him, including people's eardrums. It has also shattered glass and slammed people against the wall. When he sneezes, it is highly advisable to take cover, as the resulting blast has blown the flesh off people, leaving only a skeleton (at least among the folks in Marketing). In "The Merger", he mentions that they should "create a product that keeps your fillings from vibrating when you talk", as his fillings fly out of his mouth, which he then starts to pick up and presumably re-insert them into his mouth.

In the strips, his loud voice is represented by huge lettering and his comically huge mouth (when talking), which takes up most of the available panel space and is therefore difficult to sustain as a running joke. Howard as a recurring character is better-suited to the animated series, where his voice actor, Jim Wise, can speak as loudly as necessary.

A strip on 14 April 2008 sees Alice, Asok, and Dilbert complaining to the pointy-haired boss (PHB) about Loud Howard insisting on using his speakerphone in his cubicle. The PHB made swift response by moving Loud Howard to a newly available private office, much to the three employees' dismay.

During the TV episode "Ethics", Loud Howard holds a party, and it is shown that his house borders an airport, a railroad track, and a freeway - possibly explaining his need to shout everything.

Dildad

An unseen character in the comic strip, although he does appear in the animated series, in which his face is hidden in a fashion similar to Mammy Two Shoes from Tom and Jerry or Wilson from Home Improvement. He left Dilbert's mother during a trip to the mall in 1992 (1999 in the TV series), and lives at the all-you-can-eat restaurant in the mall because he has not eaten all he can eat. He does not have "lupus".

Liz

Dilbert's girlfriend from 1994 to 1996. He met her at a soccer game, where she rebounded a ball off his head to score a goal. Liz would constantly taunt Dilbert about their comparative levels of attractiveness and his obsession with technology, though Dilbert always took such comments in stride. Adams admitted in Seven Years of Highly Defective People that "Liz never really clicked with me", and eventually had her break up with Dilbert, after she started dating other men. She is Dilbert's longest relationship; in a series of rather ambiguous strips, it is suggested that Dilbert almost lost his virginity with her (Seven Years of Highly Defective People). Scott Adams clarified in a user interview that Dilbert is still a virgin and will remain so for a while.

Dawn and Rex

Introduced in 1989, Bob and Dawn came into the strip after Dilbert figured out that not all dinosaurs could be extinct. Bob often gives wedgies to people. Rex was born shortly after the introduction of Bob and Dawn. Bob is close friends with Ratbert.

Bob makes a cameo appearance in the teaser of one of the TV episodes, and can also be seen amongst several other prehistoric creatures in the opening title sequence.