- Family Betulaceae
- Family Bignoniaceae
- Family Bittacidae
- Family Blastodiaceae
- Family Blattidae
- Family Blechnaceae
- Family Blenniidae
- Family Boidae
- Family Boletaceae
- Family Bombacaceae
- Family Bombycidae
- Family Bombycillidae
- Family Bombyliidae
- Family Boraginaceae
- Family Bothidae
- Family Bovidae
- Family Bradypodidae
- Family Bramidae
- Family Branchiobdellidae
- Family Branchiostegidae
- Family Branchiostomidae
- family Brassicaceae
- Family Brevicipitidae
- Family Bromeliaceae
- Family Brotulidae
- Family Bruchidae
- Family Bryaceae
- Family Buccinidae
- Family Bucconidae
- Family Bucerotidae
- Family Bufonidae
- Family Burhinidae
- Family Burmanniaceae
- Family Burseraceae
- Family Buxaceae
- Family Cactaceae
- family Caeciliadae
- Family Caeciliidae
- Family Caenolestidae
- Family Caesalpiniaceae
- Family Callionymidae
- Family Calliphoridae
- Family Callithricidae
- Family Callitrichaceae
- Family Calostomataceae
- Family Calycanthaceae
- Family Camelidae
- Family Campanulaceae
