Billy Dilley’s Summer

Billy Dilley: the main protagonist, an enthusiastic and eccentric young scientist with a passion for discovery and invention.
Zeke: Billy's best friend, who is more cautious and less enthusiastic about their underground adventures but remains a loyal companion.
Marsha: another of Billy's friends, she is practical and often the voice of reason in the group, balancing Billy's impulsiveness.
Anaximander: a talking rat and Billy's pet, who often provides comic relief and has his own quirky personality.
Count Wretcher: a villainous character in the series, adding conflict and challenges for Billy and his friends.
Judy: an underground dweller who becomes an ally to Billy and his friends. She has unique knowledge about the subterranean world. She soon becomes Billy's love interest.
Tony: another underground resident who interacts with the main characters, contributing to their adventures.
Hag Witch: a mystical character who adds elements of magic and mystery to the storyline.
Zartran: a character they encounter in their adventures, often involved in various escapades and challenges.
The Mole King: a ruler in the underground world, playing a significant role in the subterranean setting of the show.