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.
Thumbelina (horse)
Thumbelina (born May 1, 2001) is a dwarf miniature horse and the world's smallest horse. She stands tall and weighs , and received the title of world's smallest from Guinness World Records. Thumbelina was born in St. Louis, Missouri. Her owners, Paul and Kay Goessling, and her handler, Michael Goessling, care for her along with other miniature horses on their farm in Ladue.