This is a list of episodes of the American animated television series The Grim Adventures of Billy & Mandy, created by Maxwell Atoms which originally aired on Cartoon Network from June 13, 2003 to November 11, 2007, but a spin-off film titled Underfist: Halloween Bash aired on October 12, 2008.
79 half-hour episodes were produced, each consisting of two or three shorter segments. Only a small number of episodes consisted of a single segment.
Note: All of these episodes can be viewed as part of Season 1 of The Grim Adventures of Billy & Mandy.
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.