B. laevis may refer to:
Balanus laevis, a barnacle species in the genus Balanus Barbichthys laevis, the sucker barb, a ray-finned fish species Bidens laevis, the bur-marigold or smooth beggartick, a flowering plant species native to the southern half of the United States
See also List of Latin and Greek words commonly used in systematic names#L