Strepsiade is an aging, unsophisticated farmer from the landed middle class who is struggling with imminent bankruptcy. Driven by a desire to evade the debts accumulated by his son's expensive equestrian hobbies, he seeks out the new intellectual movement in Athens. He hopes to learn how to manipulate logic and cheat his creditors, demonstrating a highly unscrupulous approach to his financial problems.

Socrates is the head of the Thinkery, an educational cult that subverts traditional Athenian values. He is presented as a dishonest sophist who charges a fee to teach students how to argue their way out of obligations. He dismisses the traditional Greek pantheon in favor of natural phenomena like air and clouds, embodying the amoral intellectualism that threatens conservative society.

Pheidippides is an aristocratic young man with an expensive passion for horses and horse racing. He initially regards the Thinkery and its intellectuals with disgust, preferring his traditional upper-class hobbies. He possesses a sharp mind capable of mastering the deceptive rhetoric taught by the sophists, making him exactly the kind of student his father needs.

The Clouds are the namesake of the play and serve as the patron goddesses of the Thinkery. They appear wearing cloudlike costumes and bear the faces of young women. While Socrates introduces them as modern replacements for the traditional Greek gods, they maintain subtle connections to the old pantheon and the established moral order.

Right is a personified argument who represents traditional, old-fashioned Athenian values. He advocates for piety, justice, modesty, and physical discipline, using the heroes of the Battle of Marathon as his ideal models. He firmly believes in the established moral order and warns against the hedonistic teachings of his opponent.

Wrong is the second personified argument housed at the Thinkery, embodying the opportunistic and amoral hedonism taught by the sophists. He uses spurious logic and cross-examination to deny the existence of justice entirely. He argues that indulging in pleasure and manipulating the legal system is the superior way to live.

The Second Creditor is a younger money lender who seeks to collect the debts owed to him. He uses elevated, tragic diction to complain about his financial misfortunes, making him a target for Strepsiade's newly acquired rhetorical tricks.

The First Creditor is a money lender attempting to collect on the funds that Strepsiade borrowed to finance his son's equestrian habits. He represents the legitimate financial obligations that the protagonist is desperately trying to escape.

A pupil at the Thinkery who introduces Strepsiade to the absurd scientific inquiries conducted at the school. He is completely dedicated to Socrates, proudly sharing the school's discoveries about flea jumps and gnat buzzes.

Chaerephon is an intellectual and philosopher who operates the Thinkery alongside Socrates. He is known to the Athenian public as a prominent figure in the new education movement, contributing to the school's poor reputation among aristocratic youths.