Stanley Yelnats IV
Stanley Yelnats IV is a big, sweet kid who has had bad luck all his life. When he is wrongly convicted of stealing a pair of shoes and sentenced to 18 months at Camp Green Lake, he rightly blames a generations-old curse that has plagued his family since the days of his great-great-grandfather, Elya Yelnats. At Camp Green Lake, Stanley must dig a five-foot-deep, five-foot-wide hole in a dry lake bed every day. The work transforms his fleshy body into a strong one. The social challenges of camp threaten to destroy his natural sense of empathy. But after a few missteps, Stanley risks everything to help a friend. He manages to become both kind and strong. In the process Stanley saves the life of Zero (real name: Hector) Zeroni, the great-great-great grandson of the woman Elya Yelnats wronged long ago. This ends the curse and brings good fortune to Stanley and his family.
Zero
Zero has been Hector Zeroni's nickname for a long time. It's a good indication of how others view him: as a nothing. Zero is discounted not only by the other boys assigned to his tent, but also by adults like Mr. Pendanski, the camp counselor. Zero has spent most of his life on the streets. His mother disappeared long ago, and he has fended for himself ever since. He never went to school or learned to read. He has always stolen whatever he needed—including the shoes Stanley was convicted of stealing. But Zero isn't the stupid, worthless boy people pretend he is. He has a profound mathematical and visual intelligence, as Stanley learns when he becomes Zero's teacher. Zero's intelligence repeatedly saves both boys during their short time as fugitives together. Zero is the great-great-great-grandson of Madame Zeroni, who cursed Stanley's great-great-grandfather for failing to carry her up a mountain and let her drink from a stream that flows uphill. This curse ends when Stanley carries Zero up a different mountain and lets him drink from an equally mysterious water source. It is unclear whether Zero shares Madame Zeroni's magical powers. If he does, it is possible he causes some of the lucky coincidences in the story.
X-Ray
Of the seven boys in Stanley's tent at Camp Green Lake, X-Ray is the clear leader. Throughout the story, Stanley both respects and fears X-Ray's social power. X-Ray uses his power primarily to keep the peace. Early in the story, X-Ray gives Stanley a nickname, Caveman, and makes him a part of the group. Later, even when he is angry at Stanley, X-Ray tries to prevent a fight between Stanley and Zigzag. But X-Ray also sometimes uses his power in corrupt ways. For example, he asks Stanley to hand over anything interesting he finds while digging holes. Stanley is too scared to refuse, and he hands over a small, gold object he finds. X-Ray's character doesn't change much through the course of the story. From beginning to end, he is a boy shaped by a flawed prison system—cagey, opportunistic, and expert at avoiding the wrong sort of notice from the adults in power.
The Warden
At the beginning of Holes, Mr. Pendanski tells Stanley, "There's really only one rule at Camp Green Lake: Don't upset the Warden." This rule turns out to be true for adults as well as kids. When Mr. Sir bothers the Warden unnecessarily, she hits him across the face, scratching him with rattlesnake venom in the process. The Warden is determined to find buried treasure in the dry lake bed, and she is willing to do anything to achieve her goal. Midway through the story, when Zero runs away, she even proves willing to let him die in the desert. Instead of searching for him, she has his records erased so the authorities won't show up and investigate her camp. But as terrible as the Warden is, she has her reasons. Late in the story, she is revealed to be a descendant of Trout Walker, who lost his fortune when rain stopped falling on Green Lake. Her parents forced her to spend her childhood digging for the treasure Kissin' Kate Barlow buried in the lake. As an adult she found a way to force others to do the digging for her.