B. gracilis may refer to:
Bacteroides gracilis, a species of gram negative anaerobic bacterium Barbilophozia gracilis, a liverwort species in the genus Barbilophozia Bathysauropsis gracilis, the black lizardfish, a grinner Belonolaimus gracilis, the pine sting nematode, a plant pathogenic nematode Bletia gracilis, a species of orchid Bolitoglossa gracilis, a species of salamander in the family Plethodontidae endemic to Costa Rica Bomarea gracilis, a species of plant in the family Alstroemeriaceae endemic to Ecuador Bouteloua gracilis, the blue grama, a long-lived, warm season, C4 perennial grass Brunneria gracilis, a species of praying mantis found in Argentina, Brazil, Paraguay, Uruguay and Venezuela
Synonyms Barosaurus gracilis, a synonym for Tornieria gracilis, a sauropod dinosaur from Late Jurassic Tanzania
See also Gracilis (disambiguation)