The sixth and final season of The Grim Adventures of Billy & Mandy consists of 11 episodes. This sixth season has eleven regular episodes. Midway through this season, the special episode "Billy and Mandy Moon the Moon" was shown, and the TV moviesBilly & Mandy's Big Boogey Adventure and had first aired. Also, this season is the first and only one ever to be produced in 16:9 widescreen. In this season, special debut appearances are made by Pinface ; the mummy of the Pharaoh King Popen Locken, who is Irwin's maternal grandfather; the Abominable Snowman, who is to be reaped by Grim; King Triceps, ruler of the ocean, and his daughters Hariel and Uvula ; Hector Con Carne and Major Dr. Ghastly, who try to recruit General Skarr back to their army; Lionel Van Helsing, a vampire hunter seeking to destroy Dracula; and Del Uglio, a Mexican luchador, who turns out to be Billy's identical twin brother. Lord Pain returns, now serving Mandy, instead of Grim; the Secret Snake Club is also back, now trying to avoid physical education; Nergal and his family engage in a pizza war against Billy, Mandy and Grim's own pizzeria; Nergal Junior and Irwin battle for the strong and possessive romantic love they have for Mandy; Dracula is revealed to be Irwin's paternal grandfather; Nigel Planter discovers the supernaturally dark and evil truth behind the lightning-shaped scar on his forehead; and Billy, Mandy, and Grim find themselves in Mexico to save the Día de los Muertos festivities. The episode “Billy and Mandy Moon the Moon” aired as fifth and final chapter of Cartoon Network’s Invaded event in May 2007. The event first started with Foster’s Home for Imaginary Friends, and continued with Ed, Edd, n Eddy, My Gym Partner’s a Monkey and Camp Lazlo. This event came about in 2006 when Cartoon Network was teaming up with Kraft to create a special event that was pitched as E.T the Extraterrestrial meets Kraft Mac ‘n’ Cheese. In the episode "Heartburn", the last and final regular episode of the series, Mandy temporarily overcomes her dark and sinister nature and finally romantically kisses Irwin on the lips. She quickly goes back to her old sinister, power-hungry self. There is also an Austrian therapist called Dr. Hans Frankfurt who was seen in the episode "Everything Breaks" and the Wrath of the Spider Queen movie.
