The Grim Adventures of Billy and Mandy

While Spring cleaning in the middle of November, Billy takes an old, cursed lamp from Grim's trunk. When he gives it a rub, he releases the curse Grim had warned them about: his own mother. Having three wishes to make, Billy wastes his wish by wishing to know what to wish for. Mandy wishes Billy and Grim would "shut up", so Grim never gets to make his wish. Then, Mandy decides to make the last wish to whoever makes her the happiest. In the end, Mandy wishes everyone in the world would go away, which she is glad about.

After having a nervous breakdown and leaving the house in the first episode, Billy's mother, Gladys, returns. She meets Grim again and, this time, she plans to destroy him once and for all. When Grim goes to the kitchen for a glass of water, Gladys attacks him and shatters his skeleton. In the end, Grim assures the kids that Gladys has won the battle but not the war.

With Irwin not answering the phone, Billy's parents missing and Mandy saying she wants "Billy for dinner", Billy and Grim assume Mandy is a cannibal who ate Billy's parents and friends. Looking for proof, Billy and Grim find tiki figures and arrangements for a celebration in Mandy's backyard. Ultimately, it is revealed that they are just celebrating Billy's birthday. Still, Mandy burps out Irwin's glasses.

It's Halloween, Billy, Mandy and Grim go trick-or-treating. Grim mistakes a woman for Atrocia, the host of the all-night Halloween marathon on TV and goes to talk to her. Upon looking at her face, Grim realizes his mistake; however, the woman mistakes Grim for her son, Gregory, and takes him home Gregory is now Grim, and does not have a stomach. At the same time, Billy mistakes Gregory for Grim and he and Mandy take him with them. In the end, Billy and Mandy take Gregory back to his mother and Grim goes back with them.

Nergal, the fiend from the center of the Earth, returns to the surface, emerging a carnival with him, trying once more to make friends. In the following, Billy tries to help Nergal make friends by being considerate, but Nergal fails to apply correctly his advice. When Nergal is told that Grim was forced to be Billy and Mandy's friend-slave, Nergal then decides to force the world to be his friends by turning them into dark beings similar to him. In the end, Nergal turns Billy, Mandy, Grim and even the viewer (thus breaking the fourth wall) into one before the episode ends.

Billy tells Grim to help him throw a surprise birthday party for Mandy. Then, a reluctant Grim helps Billy prepare a cake while keeping it a secret from Mandy. In the end, a somewhat surprised Mandy reveals that her birthday isn't for the next five months, something that Billy already knew about.

Billy and Irwin have been playing their favorite video game, Beasts and Barbarians, for three days non-stop. In an attempt to stop their video game addiction, Grim transports them all to a real-life version of the game. Seeing as Billy and Irwin are still doing good in their quest, Grim increases the difficulty by manipulating the traps himself. In the end, Billy, Mandy, and Grim return home escaping from a giant cyclops, while Irwin remains trapped.

Billy, Mandy, and Grim go to the museum on a school trip. There, they meet Hoss Delgado, self-appointed hunter of the paranormal, who upon spotting Grim, tries to eliminate him. Subsequently, Grim and Delgado engage in a fight. Finally, Delgado quits hunting Grim when he realizes Billy and Mandy control him. In the end, Delgado continues his own adventures and is seen fighting a werewolf.

While going to the shopping mall with Billy and Mandy, Grim spots the beautiful Eris, the goddess of discord and chaos, and tries to ask her out. However, Eris is not interested in the skinless Grim, but in the muscular Adonis. Then, Eris invites Mandy to join her in creating chaos using the Apple of Discord. Although initially they get along, Eris pulls a prank on Mandy, who subsequently tries to get revenge. In the end, Mandy fools Eris into thinking that Adonis is in the movie theater, and Eris accidentally kisses Grim.

Billy eats too much junk food that makes him feel sick. Grim prepares him a remedy using his granny's recipe, but this medicine makes a parasite to start growing in Billy's back, which Billy names Yap-yap. In the following, Billy and Yap-yap continue eating junk food, so Mandy suggest to use the antidote to the original remedy. Eventually, Yap-yap, now looking like a smaller version of Billy, detaches himself from Billy (which would have technically cured Billy without the need of him drinking the anitdote), and tries to escape from the antidote. In the end, Yap-yap drinks the antidote and is destroyed.

Billy is constantly provoked by a bully named Sperg and runs over to Grim for help.

After taking the Underworld's "Bad Book" from Grim, Billy becomes possessed by an evil entity. Then, Billy steals Grim's scythe, and uses it to open a portal to summon Yog-Sothoth. In consequence, Mandy calls for Hoss Delgado to battle Billy. It is revealed that the portal can only be sealed by throwing the book into it. As Billy eats the book, Mandy throws Billy himself into the portal, restoring everything to normal. Instants later, a portal opens up and Billy comes out and says they didn't want him there.

Mandy and her parents leave the city for a day, which makes Billy feel lonely. Then, Grim uses his supernatural powers to create a fake Mandy with pieces of dolls and toys for Billy to play with. However, the "new" Mandy is too aggressive with Billy, and he starts fearing her. The next day, the real Mandy returns home, and promptly destroys the new Mandy while in the see-saw.