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 vulnerable Kitti's hog-nosed bat ("Craseonycteris thonglongyai"), also known as the bumblebee bat, from Thailand and Myanmar is the smallest mammal, at in length and in weight.