Lord Grudgemunger is a character and villain from the Season 1 finale episode, "The Rock of Sages", as well as the main antagonist of the episode.  He later appeared at the end of "The Enchanted Forest Ranger" in Season 2.
In "The Rock of Sages," it is revealed that in the past of Jollywood, Lord Grudgemunger had played a dirty trick on the Seven Sages forcing them to look away from the gem and snatched it. Luckily, the Seven Sages had tricked him into looking away from the gem claiming there to be a Loch Ness Monster on the other side. Dopey grabbed the rock from Lord Grudgemunger's hands and Jollywood was saved. The Seven Sages then decided to take each piece of the Rock of Sages with them and travel to each of the seven corners of the globe to prevent such a disaster from happening again, or rather, until the present day.
In the series
In present day Jollywood, Hildy and Grim cast a spell that will destroy the kingdom by a eruptive volcano unless Queen Delightful resigns from her throne and she does, by crowning Hildy as the new queen. However, the Glooms themselves are unable to stop it, and the 7D has to find the seven gems that make up the Rock of Sages to reverse the spell. After they do, Lord Grudgemunger finally reappears, revealing his true identity after serving as the episode's narrator (the volcano plot was his idea all along). He gained the gem and, now more powerful by robbing the kingdom of all magic, he conjured a monster from the top of the volcano. However, once again he is defeated thanks to Dopey adding several pages to his storybook that shows his demise (by falling off a cliff) and the return of all magic to the kingdom, and Jollywood is restored to its beautiful glory.
In "The Enchanted Forest Ranger" he is among a group of villains headed by a mysterious squirrel.
Lord Grudgemunger is light green skinned with a long, crooked nose and long blue hair and eyebrows. His clothing consists of a black robe with a large red collar. He has two golden rings on each hand. He also has a golden crown on his head with purple crescents and red stars.
"The Rock of Sages"
"The Enchanted Forest Ranger"