When does The Grim Adventures of Billy & Mandy return?

Billy & Mandy began as a segment on Grim & Evil, from which it was a spin-off, along with sister series Evil Con Carne, on August 24, 2001. The series is centered around the exploits of Billy (Richard Steven Horvitz), an idiotic and happy-go-lucky boy; Mandy (Mandy), a deadpan, cynical and cold-hearted girl; and Grim (Greg Eagles), a Jamaican-accented Reaper. Billy and Mandy use Grim's supernatural abilities to venture into supernatural locations or environments, such as the Underworld, or the Netherworld.
The series is centered around the exploits of Billy (Richard Steven Horvitz), an idiotic and happy-go-lucky boy; Mandy (Grey DeLisle), a cynical, cold-hearted and grumpy girl; and Grim (Greg Eagles), a Jamaican-accented Reaper. Billy and Mandy use Grim's supernatural abilities to venture into supernatural locations or environments, such as the Underworld, or the Netherworld, inhabited by an assortment of grotesque monstrous beasts. Famed fictional monsters including Dracula, the Wolfman, and the bogeyman are also comically depicted in the series.