List of The Grim Adventures of Billy & Mandy episodes

Everything Breaks: As Billy behaves more reckless than ever and cannot stop breaking everything in sight, Mandy thinks he should go some place where he can release all his urge to destroy until he gets tired of it. Mandy, Grim, and Irwin go to Level 9, home of the fearsome warrior Lord Pain, to convince him to take Billy. Billy receives psychological treatment and it is revealed that his desire to destroy stems from lack of attention when he was younger. Lord Pain abducts him, and together they start destroying everything in Level 9, which seems to be is uninhabited. Billy is still not satisfied, so he and Lord Pain return to Endsville and carry on breaking everything.

The Secret Snake Club vs. P.E.: As Billy realizes the three geeks of the Secret Snake Club get doctor's notes to avoid Physical Education (P.E.) class, he wants to know their secret to avoid the class too. All the boys in the class join the club and all, except Billy, get doctor's notes from Billy's dad, who poses as a doctor. While Billy is the only one exercising in the class, the Snake Club summons a snake to destroy the gym. Since the invoked snake is tiny, Sperg uses Grim's scythe to make it a giant. Mandy and the other girls beat the boys and their snake because they did appreciate the P.E. class as an outlet for their aggression.

Billy Gets an "A": When Billy fails an important test, the result of which will go into his permanent record, he asks Grim to magically alter his grade from an "F" to an "A"; as Grim reluctantly changes the grade, Billy becomes a genius, but reality is thrown completely off balance. Mandy and Grim go back in time to stop the past Grim from helping Billy, but it does not work. They keep going back in time to different epochs, each time meeting another Grim, eventually trying to stop Billy's ancestors from conceiving him, but nothing works. After meeting Billy's distant dinosaur relative, the episode ends abruptly as Grim wonders what the end of this could be.

Nergal's Pizza: When Nergal comes to tell the guys about his new pizza joint, Grim thinks he can do better by using his Granny's recipe. A pizza war ensues between Nergal's Pizza and Grim's Pizza, with each pizzeria launching TV ads and discrediting each other. Nergal Jr. uses his shape-shifting abilities to infiltrate Grim's pizza and replace Granny Grim's hot sauce with a "ghastly elixir". The result is pizzas becoming monsters and attacking the city, and the citizens developing parasites similar to Nergal. Nergal and his family leave the city just as Grim's sauce explodes.

Company Halt: As General Skarr is once again annoyed by Billy, Hector Con Carne and Major Dr. Ghastly arrive in his house with the intention of luring him back to the recently relaunched Evil Con Carne world domination organization. Although initially refusing to rejoin, Skarr later accepts with the condition that Billy and the other neighbors be destroyed. After a few weeks of living together and preparations, Evil Con Carne's ultimate weapon is revealed to be an army of tanks that shoot giant rubber bands. Skarr's all-out attack over the neighborhood is foiled when Billy tricks Hector into shooting Skarr's garden and they get into a fight.

Special Guest Stars: Phil LaMarr as Hector Con Carne, Frank Welker as Boskov, Grey DeLisle as Major Dr. Ghastly

Waking Nightmare: When Mandy finds Billy playing with Grim's gigantic dog, Cerberus, she tells Grim to keep Billy under tight control because she needs a good night of sleep to be ready for the next day's test. With a little persuasion from his own dad, Billy tries to wake up Mandy at night, so she will fail the test and he can score higher than her for the first time. After Grim spends the night guarding Mandy's house from Billy, the latter succeeds in waking up Mandy. It is revealed that this Mandy is in fact Irwin, used as a decoy by the real Mandy, who slept in her dog's house. Mandy passes the test, and Grim is punished for not guarding her properly.

The Greatest Love Story Ever Told Ever: When Irwin lacks the courage to ask Mandy to go with him to the Valentine's Day school dance, he tells Nergal Jr. to do it for him. Mandy mistakes Junior's invitation for his own, and surprisingly accepts to go with him, which naturally makes Irwin jealous. With the ill advice received from his father, to be possessive with Mandy, at the dance Junior becomes overprotective of her, that eventually he and Irwin start fighting, throwing punch at each other and ruining the ball. It is revealed that this was Mandy's true intention all along so that no one could enjoy Valentine's Day.

Dracula Must Die!: When vampire hunter Lionel Van Helsing prepares to kill Dracula, Billy, Mandy, and Grim arrive to stop him since Dracula is just senile and harmless. Van Helsing reveals the source of his hatred: in the past, he and Dracula were "best friends forever", until Dracula used his irresistible dance moves to marry Tanya, the woman of his dreams. Tanya arrives too, revealing that she is none other than Irwin's grandmother, making Irwin one-quarter-vampire on his father's side and half-mummy on his mother's side. Van Helsing leaves, but Dracula is unsatisfied with his newfound family of nerds.

Nigel Planter and the Order of the Peanuts: When Billy, Mandy and Grim go to a joke shop, they find the owner is former boy wizard Nigel Planter, who reveals that his powers diminished and was kicked out of Toadblatt's School of Sorcery. Planter steals Grim's scythe and heads to the school to exact revenge on those who wronged him. The guys seek the help of Planter's sworn enemy, Lord Moldybutt, to find the school. Grim recovers his scythe, and Moldybutt turns out to be in fact only a real estate agent, who informs Planter that he is the heir to the "Peanuts by Planter" farming company.

El Dia de Los Muertos Estupidos: When Billy's dad drives Billy, Mandy and Grim to the hamburger restaurant, they somehow end up in Mexico. There, the people are celebrating Dia de los Muertos, but local kids say it may be the last celebration ever, because Del Uglio, a masked and ugly luchador, is set on stealing the "Golden Nose of Chipotle", a prehispanic relic on which the festivity is based. To get to the nose, Del Uglio has one half of the map, while the other half is held by his lost twin brother, who turns out to be Billy. Grim defeats Del Uglio, but it is Mandy who keeps the golden nose for herself, which makes her rich.

A scene of Endsville two weeks into the future shows a dystopian world ruled by the "Lord of Horror", who wields the all-powerful artifact known as "Horror's Hand". At the same time, two robotic replicas of Billy and Mandy are sent into the past, to stop the real Billy and Mandy from interfering with the current events.

In the present, Grim goes to reap General Skarr, who accidentally got a big wound in his torso. Due to Billy and Mandy's meddling, Skarr escapes, and they make a big mess in the city. Following his failure to be an effective Reaper, Grim is taken to the Underworld Court, presided by Judge Roy Spleen, where he is sued for misuse of his powers by his nemesis, the Boogeyman. Grim is found guilty, is stripped of his rank and magical scythe, and he, Billy, Mandy, and Irwin are sentenced to be exiled. Boogey volunteers to carry on the sentence by taking the prisoners aboard his ship, and dropping them off in a river of fire; he plans to do this while he sails to obtain Horror's Hand, an object capable of transforming him into the scariest, strongest and most powerful being in existence.

The group of Billy, Mandy, Irwin, and the powerless Grim, escapes from Boogey's ship when Billy distracts Boogey and his crew with the song "Scary-o", and set themselves to reach Horror's Hand before Boogey does. They eventually meet Horror, the guardian of the Hand, at the same time Boogey and his crew arrive. To decide who will have the honor to battle Horror for his Hand, the heroes and Boogey participate in a challenging obstacle course, which the heroes win against all odds. After dispatching Horror with ease, Billy, Mandy and Irwin reach for the Hand, but it defends itself by making their worst nightmares come to life. Boogey gets hold of Horror's Hand, but he turns out to be the least scariest creature ever, seriously injuring himself, and being abandoned by his own crew.

On a rainy day, giant spiders appear in Billy and Mandy's school and start kidnapping the children one by one. Grim presumes this is somehow related to his past, but does not figure it out until he receives a message saying that Velma, the Spider Queen, an old good friend from high school, is responsible for it. Meanwhile, Billy meets with Jeff the Spider, who informs him that he is precisely marrying Velma. After trying to recover a talking carton of chocolate milk from Jeff, Billy and Jeff get into a fight, and Jeff looks angrier than ever before.

Upon meeting in the school's football field, Velma tells Grim that she has finally come to devour his skull and absorb his magical and supernatural powers, since one hundred thousand years ago, Grim had cheated and robbed her from the possibility of becoming the Reaper in a scare election. Converting the school into her own palace, and with help from the Dark Elves, Velma captures Mandy, Mindy, and Grim, and proceeds to devour the latter's skull. When Velma cracks open Grim's skull, his thoughts start coming out in the form of light blue light, and she is able to see his past memories.

Grim's skull is connected to a projection screen, and the story on how he became the Reaper is shown. It is revealed that an election was held in the Underworld's high school to choose the Reaper, in which students had to vote on the scariest participant. Velma was the scariest contestant and she was getting most of the votes over the pathetic Grim and the Boogeyman. Boogey decided to tamper with the ballots, and Grim in turn decided to help Velma by filling the ballot with votes for her, but she got the impression that Grim was the cheater and ran away. In a fit of anger for what Boogey had caused, Grim used the prototype scythe in a spectacular fashion to scare Boogey off. The people that had not yet cast their vote voted for Grim, who became the new Reaper. While the story is being told, Mandy and Mindy form a temporary alliance to fight the spiders, and also Billy conquers his arachnophobia, and fights the spider-cow centaur-like extraterrestrial from the milk carton.