Princess Chlamydia is a stomach bacterium that lives inside Twayne Boneraper's body, as seen in the episode "Journey to the Center of Twayne".

Leonard Powers shrinks Mark Lilly, Francis Grimes and himself to enter Twayne's body to catch Jerry McMillan. They are caught and brought to a bacterial village. Leonard casts a translation spell to communicate with them. They meet Princess Chlamydia there.

She and Francis Grimes quickly get married. However, Jerry is enraged to see them and burns the village down. The princess' father is killed by the fire. The three men go after Jerry and Grimes eventually gets his revenge by killing Jerry with a bone spear.

Later, Princess Chlamydia say goodbye to her new husband as the men begin to grow back to their original size, threatening Twayne's life. She still manages to keep in touch with Grimes through a cellphone left behind inside Twayne's stomach.