Gregory, affectionately nicknamed Greg, is Wirt's younger half-brother. He is a very energetic boy who always has a smile on his face and very wild ideas on his mind. He's endlessly fascinated by everything, including things that would normally seem scary such as the ghost in Mad Love. He has a habit of wandering out on his own. He has a pet frog which he found before his descent into the Unknown. He gives it a different name every chapter (Kitty, Doctor, George Washington, etc) but ends up naming it Jason Funderburker in Chapter 10. He also carries a rock (that was stolen from Mrs. Daniel's garden), that will randomly make Rock Facts. He is the deuteragonist of the show.
He is voiced by Collin Dean.
Gregory sounds and appears to be very young. He is very small and plump, compared to other characters. He wears a white shirt with a small brown ribbon, light green overalls with round black buttons, and black shoes with high white socks. He also has a brown satchel and wears a tin tea kettle on his head. Greg's hair is also considerably neater compared to his brother's before their descent into the Dark Forest.
Greg is the happy-go-lucky optimist of the trio, often remaining positive and unconcerned even in the face of danger and impossible odds. This is likely due to the fact that, being so young, Greg is incapable of grasping the true nature of he and his brother’s situation and instead views everything that happens to them with a light-hearted innocence. His outlook remains unaffected even as the Beast tries to tempt him into despair. He’s a free spirit and is content marching to the beat of his own drum, showing little inhibition when it comes to expressing himself and often getting sidetracked/wandering away from the group whenever it suits him. Greg wholeheartedly believes that he can do anything when he sets his mind to it, and he refuses to give up in even the bleakest of situations.
Greg’s optimism isn’t easily shaken by Wirt’s dour outlook— in fact, he seems to take everything his brother says quite literally, and tends to puts a positive spin on Wirt’s negativity rather than be deterred by it. He remains unaffected by his experiences in The Unknown even after their journey has ended, and happily recounts the tale as if it were a grand adventure.
- Gregory is an animal lover, given his friendly interaction with his frog, the dog and black turtles, and he dresses up as an elephant (sort of) for Halloween.
- Greg and his father have both suggested to Wirt that he join the high school's marching band.
- Greg's Halloween costume is an elephant.
- Like Wirt, Greg seems to possess some creative talent, his impromptu outbursts of song and ability to compose lyrics off the top of his head not unlike his brother's poetic musings.
- Greg was shown knowing how to play the trumpet in Chapter 8, Babes in the Wood.