| Bacillariophyta | EUKARYA>CHROMALVEOLATA>HETEROKONTAE>BACILLARIOPHYTA |
| Bangiophceae | see Rhodophyta |
| Basidiomycota | EUKARYA>OPISTHOKONTA>UNIKONTA>FUNGI>DIKARYA>BASIDIOMYCOTA |
| Basidiomycotina | see Basidiomycota |
| Batrachomorpha | EUKARYA>UNIKONTA>OPISTHOKONTA>ANIMALIA>BILATERIA>DEUTEROSTOMATA>VERTEBRATA>GNATHOSTOMATA>TETRAPODA>BATRACHOMORPHA |
| Betaproteobacteria | EUBACTERIA>PROTEOBACTERIAE>BETAPROTEOBACTERIA |
| Bicosoecida | EUKARYA>CHROMALVEOLATA>HETEROKONTAE>BICOSOECIDA |
| Bilateria | see Animalia |
| Blastocladiomycota | EUKARYA>OPISTHOKONTA>UNIKONTA>FUNGI>BASAL FUNGI>BLASTOCLADIOMYCOTA |
| Brachiopoda | EUKARYA>UNIKONTA>OPISTHOKONTA>ANIMALIA>METAZOA>BILATERIA>PROTOSTOMATA>SPIRALIA>TROCHOZOA>BRACHIOZOA>BRACHIOPODA |
| Brachiozoa | see Spiralia |
| Bryophyta | EUKARYA>ARCHAEPLASTIDA>VIRIDIPLANTAE>STREPTOBIONTA>EMBRYOPHYTA>BRYOPHYTA |
| Bryopsida | see Bryophyta |
| Buxbaumiopsida | see Bryophyta |
