Gas giant
The smallest known extrasolar planet that is likely a "gas planet" is Kepler-138d, which has the same mass as Earth but is 60% larger and therefore has a density that indicates a thick gas envelope.
Smallest organisms
The Etruscan shrew ("Suncus etruscus"), is the smallest mammal by mass, weighing only about on average. The bumblebee bat has a smaller skull size. The smallest mammal that ever lived, the shrew-like "Batodonoides vanhouteni", weighed only .