* Decker: The protagonist of the story, a young boy who is fascinated by the melonheads. He often ventures to the junkyard to learn more about them.
* Marcy: Decker's younger sister, who is initially afraid of the melonheads but later becomes curious about them as well.
* The Melonheads: Mysterious and enigmatic creatures with round, melon-shaped heads who reside in the junkyard. They are often rumored to be dangerous and malevolent.
Supporting Characters:
* Mr. Melonhead: The leader of the melonheads, who has the most prominent melon-shaped head and seems to have some sort of connection to Decker's family.
* Mrs. Melonhead: Mr. Melonhead's wife, who exhibits a motherly and nurturing attitude toward Decker and Marcy.
* Billy: A neighborhood bully who teases Decker and Marcy about the melonheads.
* Mr. Parks: Decker and Marcy's father, who is a hard-working and loving father.
* Mrs. Parks: Decker and Marcy's mother, who plays a supportive role in the family.