Groups Of Creatures Mentioned

The creatures in the series resemble their real-life counterparts in almost every way, aside from being very large (most of them being bigger than the humans) and able to speak in English.

• Crawlers (Cockroaches): They are said to be cowardly and are not treated well by the other species. They call Boots "Princess".
• Spinners (Spiders): They provide several types of silk.
• Fliers (Bats): Fliers are on very good terms with humans. They go on quests together, protect each other, and sleep in the same rooms. These creatures "bond" with their human counterparts in a very special ceremony.
• Gnawers (Rats): They are the penurious of the story. Most of the Gnawers are rude and unmannerly.
• Shiners (Fireflies): All Shiners eat too much, are lazy and unreliable. A Shiner who has left more than enough food for others is unheard of. Most Shiners are competitive with one another. Introduced in book 2.
• Nibblers (Mice): Are allied to the humans. Introduced in book 3.
• Stingers (Scorpions): Are allied by the humans by book 4.
• Diggers (Moles): Introduced in book 5. They are the true founders of the Underland. Gregor discovers that when Bartholomew of Sandwich decided to settle, he tried to kill all the Diggers in order to have the land he wanted. This is the biggest reason humans are called "Killers", as this was the Underland's first impression of them.
• Twisters (Snakes): Introduced in book 4.
• Hissers (Lizards): Introduced in book 3.
• Cutters (Ants): Enemies of all warmbloods (as opposed to coldbloods). Introduced in book 3.
• Slimers: (Snails): Are mentioned by Howard in book 4.

Minor Characters .

• Nerissa: Luxa's cousin who foresees what either is going to happen or what already did. Ripred describes her flip-flopping through time like a fish in the shallows.
• Solovet: Luxa's grandmother and Vikus's wife; head of the Regalian army.
• Dulcet: a servant in Regalia. She watches the young in the palace.
• Perdita: an Underland soldier
• Grace: Gregor, Lizzie and Boots' mother
• Grandma: Gregor, Lizzie and Boots' grandmother after whom Boots (Margaret) was named.
• Mrs. Cormaci: A family friend to Gregor's family
• King Gorger: The king of the gnawers
• Queen Wevox: a giant spinner.
• Gox and Treflex: two spinners
• Lizzie: Gregor and Boots' sister, mentioned more than once.
• Mareth: One of Regalia's soldiers

Main Chararcters .

• Gregor: The protagonist of the story. He falls into the Underland with his sister, Boots.
• Luxa: An Underlander, and the soon-to-be queen of Regalia.
• Ripred: A trustworthy gnawer with deadly fighting skills and sharp intelligence, he fights alongside the humans.
• Ares: A flier, first Henry's bond, then Gregor's. He is described as jet black, and strong.
• Henry: An Underlander, and Luxa's cousin on the Royal side.
• Vikus: Luxa's grandfather and Solovet's husband. Helps Gregor understand the history of the Underland.
• Aurora: A flier, Luxa's bond. A golden color.
• Boots (Margaret): Named after her grandma, Boots is Gregor's cheerful, two-year-old sister who is afraid of very little. Never met her father.
• Temp and Tick:The crawlers that call Boots "princess"
• Dad: Gregor is trying to save him from the Underland.