The Grass Lands, sometimes referred to as the Grass Kingdom, is an area of the Land of Ooo in Adventure Time. It is an area of green, grassy fields and the location of Finn and Jake's Tree Fort. The area is also called the Verdant Plains on one map of the Land of Ooo. The Grass Lands share borders with the Candy Kingdom, the Ice Kingdom and the Fire Kingdom. Other kingdoms such as the Goblin Kingdom and Hot Dog Kingdom are shown to exist within the grasslands.
- Tree Trunks
- Banana Man
- Hot Dog People
- Two-Headed Duck
- Battle Cube
- Fuzzy Friends
- House People
- Mama Jiggler
- Science Cat
- The Owl
- The Porcupine
- Lenny the Beaver
- Tree Witch
- Stanley and his family
- Grass People
- Old Ladies
- Marceline (Many years prior to "Evicted!")
- Ash (Many years prior to "Evicted!")
- Flame Princess ("Hot to the Touch" – "Earth & Water")
- Ice King (temporarily from "Earth & Water" – "Play Date")
- Shoko (Died here ~300 years ago)
- Villages and Kingdoms
- In "Business Time," Hot Dog Princess is shown living in the Grass Lands in a small doghouse, surrounded by a large fence.
- Joshua's dungeon is located underneath the Grass Lands.
- In "Incendium," Jake claims that Finn is the Prince of the Grass Lands, and himself a Baron.
- In "Princess Cookie," Jake unofficially makes Baby-Snaps Princess of the Grass Kingdom.
- In "Burning Low," Princess Bubblegum, ruler of Candy Kingdom, is seen collecting taxes from Finn and Jake indicating that some locations of the Grass Lands are under the authority of the Candy Kingdom and possibly other kingdoms.
- In The Adventure Time Encyclopædia, Marceline states that the Snail, along with many other characters, lives in the Grass Lands.
- It is a playable area in the DS/3DS game Adventure Time: Hey Ice King! Why'd you steal our garbage?!!