The parabasalids are a group of flagellated protists within the supergroup Excavata. Most of these organisms form a symbiotic relationship in animals; these include a variety of forms found in the intestines of termites and cockroaches, many of which have symbiotic bacteria that help them digest cellulose in woody plants. Other species within this supergroup are known parasites, and include human pathogens.

The parabasalids are a group of flagellated protists within the supergroup Excavata. Most of these organisms form a symbiotic relationship in animals; these include a variety of forms found in the intestines of termites and cockroaches, many of which have symbiotic bacteria that help them digest cellulose in woody plants. Other species within this supergroup are known parasites, and include human pathogens.