Cognomen Rainn (ฝน 
, Rainn 
, 雷恩 
) , around the world, is a rare surname. The cognomen Rainn is characteristic of Myanmar, where it is quite a rare surname, Thailand, where it is a very rare surname, and Russia, where it is an extremely rare surname. Measured by absolute frequency, this name is the most popular in Myanmar, Thailand, and India. More frequently, Rainn is the forename as well as the last name.