This season includes the 13 episodes originally produced as part of Grim & Evil, although only those which are part of The Grim Adventures of Billy & Mandy are summarized in 8 episodes. This season introduces the three main characters, the extremely happy-go-lucky Billy, the sour and cruel Mandy, and the Grim Reaper himself, who is condemned to spend his time being the two kids' best friend. Recurring characters that are presented are Billy's family and friends, including his dumb father, Harold, his slightly mentally unstable mother, Gladys, his spinster aunt, Sis, and his best friend, Irwin. Also introduced are Nergal, the fiendish, supernatural humanoid living lonely in the center of the Earth; Hoss Delgado, the macho spectral exterminator; Eris, the beautiful and crazy goddess of chaos who wields the Apple of Discord; and Sperg, the school bully. Other minor characters that would recur include the timid Pud'n; Atrocia, the host of a TV show that Grim watches; and Granny Grim, always ready to provide supernatural recipes and potions.