Planet
The smallest known planet is PSR B1257+12A, one of the first extrasolar planets discovered, which was found in 1992 in orbit around a pulsar. Its mass is roughly half that of the planet Mercury. The smallest known planet orbiting a main-sequence star other than the Sun is Kepler-37b, with a mass (and radius) slightly higher than that of the Moon.
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.