The American animated television series Grim & Evil was created by Maxwell Atoms for Cartoon Network. It consists of two segments which were eventually spun off into their own series: The Grim Adventures of Billy & Mandy and Evil Con Carne.

The Grim Adventures of Billy & Mandy follows two children: a dimwitted yet well-meaning boy named Billy (voiced by Richard Steven Horvitz) and a brilliant yet sinister girl named Mandy (voiced by Grey DeLisle). After winning a limbo game to save Billy's pet hamster, the two gain the Grim Reaper (voiced by Greg Eagles) as their best friend for eternity and come across many supernatural or otherworldly characters and locations throughout the series.

Its sister show, Evil Con Carne, follows the brain of a playboy who wants to rule the world with his general, Skarr, and his lover, Major Doctor Ghastly. Since Hector Con Carne is attached to a bear named Boskov, Hector wants to find the rest of his body parts and take over the world.

Introduced in The Grim Adventures of Billy & Mandy Main In 2021, Maxwell Atoms, who has Asperger syndrome himself, confirmed that Billy, Mandy and the Grim Reaper are on the autistic spectrum. He likens Billy to "the fun and joyous inner-world where [Atoms likes] to spend [his] time" in contrast to Mandy, Mandy to "the cold, rational way [he] learned to view the world in order to survive", and Grim as "the moral mediator between the two."

Billy

William "Billy" is a human boy with a profound intellectual disability, having been outperformed by a shovel and two candy bracelets on an IQ test, though he acts like a smart-aleck. Mandy is Billy's best friend, though she treats him more like a servant than a friend. It has been hinted several times that Billy may have underlying feelings for Mandy that he does not fully realize. Billy is far kinder to Grim than Mandy is; while he almost always goes against Grim's advice and uses him as a plaything, he appears to genuinely like him and often tells Grim that he is his "best friend".

Due to Billy's foolish desires, which he orders Grim to bring about, he is often the cause of Grim and Mandy's mishaps. Although good-natured, he has occasional fits of stubbornness and rage, which shows insanity that even Mandy seems to fear. Billy is also scared of clowns and spiders, resulting from a childhood incident where Bun-Bun snuck into his room and tormented him with spiders.

Mandy

Amanda "Mandy" is a human girl with a sinister, manipulative nature despite her appearance. Mandy has been known to domineer everybody around her without fear, and the few things that she likes include junk food, television, and all things dark and melancholy. She also possesses a strong lust for power as revealed in an episode providing insight to the future of the town of Endsville, in which Mandy has enslaved all of its citizens and evolved herself into a large caterpillar-like creature. In Underfist: Halloween Bash, after the Underworld invades Earth, Mandy seizes power as the new President of the United States, with Grim and Billy serving as her weapons experts, the trio rewarding Underfist for saving the world.

Throughout the series, Mandy rarely smiles, and her facial expression remains perpetually disgruntled. Mandy smiling is shown to be the end of the world; in the episode "My Fair Mandy", all of reality is distorted, resulting in the series swapping premises with that of The Powerpuff Girls, another Cartoon Network animated series.

The Grim Reaper

Evergrimskull "Grim" Death a.k.a. the Grim Reaper is the personification of death appearing as a skeleton wearing a black, hooded cloak and armed with a scythe, who serves as a psychopomp between the realms of the living and the deceased. Grim was born around 137,000 years ago at the time of the Stone Age and speaks with a Jamaican accent. The continuity of how Grim gained his status and powers varies between episode. In the television film Wrath of the Spider Queen, Grim was elected to his position as the Grim Reaper while in middle school; in "A Grim Prophecy", it is shown that he has been the Grim Reaper since childhood. His long scythe is the source of nearly all his supernatural abilities, and possesses many magical capabilities and qualities; although he is still capable of using some incredibly powerful magic spells without it, these instances are quite rare.

After losing a limbo contest to Billy and Mandy after they cheated, Grim is fated to be their "best friend" forever. A contract legally binds him to them, such that if he were to ever break his friendship with them prematurely, he would be forced to spend eternity in a jail in the underworld as a result of violating his contract. Despite this however, he has often tried various ways to get out of this servitude. Though Billy is friendly towards him, Mandy treats him dominantly, and this angers and irritates him to the point where he constantly fantasizes about killing both of them. However, there have been instances that show that he does indeed care for them. His adaptation to daily life also leads him to neglect his duties as a Master of the Underworld and, eventually, not even care about who uses his scythe.

Supporting

Irwin Dracula

Irwin, later Irwin Dracula, is a nerdy boy and a close friend of Billy's. Unlike Mandy and Billy, who show no signs of fear for the frightening, supernatural and magical beings and settings around them when using Grim's magic to venture into the underworld, Irwin has displayed more signs of cowardice in such situations and seems to be more easily terrified than his friends when he accompanies them on such trips. Irwin's mother and maternal grandfather are mummies, while his paternal grandfather is Dracula.

In rare instances Irwin is shown to have an evil, darker and power-hungry side to his personality. In the episode "Heartburn", Mandy discovers everyone's true heart through the use of Grim's special camera, but is greatly shocked when she discovers that one side of Irwin's heart looks like hers in a creepy way. Irwin explains that he was born evil, but had a change of heart when his father showed him the meaning of respect, friendship, and love.

Billy's family Harold (voiced by Richard Steven Horvitz) is Billy's equally dimwitted and idiotic father. Harold resembles his son in appearance and personality, sometimes displaying even more stupidity than Billy himself. Harold's employment is unknown and varies between episodes. Despite his low IQ, Harold was accepted in Harvard and is a former Navy Seal. Gladys (voiced by Jennifer Hale) is Billy's mother. She is a loving, tolerant, and patient, yet mentally unstable woman. This is brought on by having to deal with her family, and Grim as a guest. She has a severe facial tic, which usually appears when Billy is misbehaving, when her authority is challenged, or whenever Grim is present, and has also developed nervous breakdowns. Despite so, Gladys cares deeply for Billy and Harold, although when Harold gets fired for doing something so stupid or whenever Billy is really disobeying her or acting up, she does have large outbursts of rage. Milkshakes (voiced by Grey DeLisle) is Billy's cat. In spite of his lack of significance in the series, on a couple of occasions he has played a key role; his body has been overtaken supernaturally on two occasions in the past; once by a bookworm to help Billy in school and on the other instance by an enraged, vindictive Mandy, whose body had been possessed by a clowning Billy earlier in the episode. Nergal (voiced by David Warner (2001–2002); Martin Jarvis (2003–2008)) is a British accented, black-skinned supernatural devil with green eyes who is the god of war and wears a business suit. He is loosely based on the Mesopotamian deity of the same name. Nergal is able to shapeshift and sprout tentacles from his back that can electrocute others or turn them into beings resembling himself. What Nergal desires most is having friends, once stating that it is quite lonely in the center of the world Aunt Sis (voiced by Grey DeLisle) is Harold's sister and Billy's paternal aunt. She was a spinster who had experienced four-and-a-half-minutes of love in her "pathetic, lonely life" before finally finding her match in the equally lonely demon Nergal. Nergal Jr. "Junior" (voiced by Debi Derryberry) is the son of Nergal and Billy's aunt Sis, and Gladys and Harold's nephew. Like his father, he has the power to shapeshift and most of the time he appears in the form of a child. It is revealed in the episode "Son of Nergal" that his true form resembles a black octopus-like creature. Like his father, Nergal Jr. is lonely and terrorizes others out of desperation.

Mandy's family Phillip "Phil" (voiced by Dee Bradley Baker) is Mandy's father and Claire's husband. In "Keeper of the Reaper", he states that when Mandy was born, wolves came and tried to take her as their own, but he sometimes wonders if they were right to stop them. Claire (voiced by Vanessa Marshall) is Mandy's mother and Phil's wife. She, like her husband, is also terrified of her daughter. Saliva (voiced by Jess Harnell, later Richard Horvitz) is Mandy's dog.

Irwin's family Richard "Dick" Dracula (voiced by Phil LaMarr) is Irwin's father. He is a middle-aged Dhampir (half-human and half-vampire), but is never referred to as a vampire and does not appear to possess any vampiric powers. He is married to a mummy named Judy, who is Irwin's mother and due to her being a mummy makes Irwin half-mummy, one quarter human and one quarter vampire. Irwin's father insists that their unusual pairing leaves "a lot of questions that don't need to be answered". Judith "Judy" Lockin' Dracula is Irwin's mummy mother and wife of human/vampire Richard Dracula. Since Judy is undead, she lives in the basement (resembling an Egyptian tomb). Tanya "Grand-mama" Dracula (voiced by Phil LaMarr) is Dick's mother, Judy's mother-in-law and Irwin's paternal grandmother. Despite her angry demeanor, she seems to care for Irwin, but will sometimes embarrass him. In "Dracula Must Die!", it is revealed that when she was young, Tanya was a very lovely young woman who could really kick-butt with karate and that she married Dracula because he was a great dancer despite him being a vampire. Lord Dracula (voiced by Phil LaMarr) is a legendary vampire, Irwin's paternal grandfather, and Grim's childhood hero. When he danced for Tanya she instantly fell in love with him, but he ran away from her when she beat him up, thinking he was a bat. He frequently refers to himself in the third person. Dracula's appearance and mannerisms are patterned after the blaxploitation films of the early 70's, most notably Blacula, as well as Fred G. Sanford of Sanford & Son. Melvin Dracula, Irwin’s older brother

School members Mindy (voiced by Rachael MacFarlane) is the queen bee of the school attended by all of the child characters featured in the program (and is always shown in her school clothes regardless of being outside of school). Mindy shares a rivalry with Mandy, whom she looks down upon and considers to be unattractive and inferior in comparison with her. Being very self-important, Mindy snubs her peers and has a powerful competitive edge. Sperg (voiced by Greg Eagles) is a bully who picks on Billy, Irwin, Pud'n, and other kids to no end. He is a husky boy whose preferred method of terrorizing other kids is by administering his lethal wedgies. Despite his physical strength, he is frightened of Mandy because of her toughness and cynical attitude. Sperg has dreams of moving to New York City and having a career on Broadway when he grows up.