Stanley Yelnats IV: The protagonist, a 14-year-old boy wrongly accused of stealing a pair of sneakers. He is sent to Camp Green Lake, a juvenile detention camp where the boys are forced to dig holes all day.
Zero: A skinny, quiet boy who is Stanley's best friend. He is also wrongly accused of a crime and sent to Camp Green Lake.
Kissin' Kate Barlow: A legendary outlaw who was once a teacher in Green Lake before it dried up. She was accused of stealing from a man named Sam, who was a descendant of the original owner of the land, and is believed to have buried her treasure somewhere in the area.
Sam: A former slave who fell in love with Kissin' Kate Barlow and was wrongly accused of stealing by a group of white men. He is believed to have been the one who cursed Green Lake, causing it to dry up.
Mr. Sir: The cruel and abusive warden of Camp Green Lake. He is obsessed with finding Kissin' Kate Barlow's treasure and forces the boys to dig holes in the hopes of finding it.
The Warden's Daughter: A mysterious girl who appears to be more than she seems. She has a connection to Kissin' Kate Barlow and may hold the key to the mystery of Green Lake.
X-Ray: The leader of the group of boys at Camp Green Lake. He is tough and resourceful, but also cruel and manipulative.
Squid: One of the boys at Camp Green Lake. He is known for his strength and his ability to pick locks.
Armpit: One of the boys at Camp Green Lake. He is so-called because he has very smelly armpits.
Zigzag: One of the boys at Camp Green Lake. He is known for his quick wit and his ability to tell stories.
The Warden's Mother: A seemingly innocent old woman who is revealed to be a key player in the events that led to the curse of Green Lake.
This list only covers the main characters. The story is filled with supporting characters, each playing a role in the unfolding events.