Ran Ran is a doll that looks like a female version of Chiaotzu, which he considers his wife. She made her first and only appearance in the movie Dragon Ball: Mystical Adventure, which is a retelling of the events of early Dragon Ball.
As part of a plan to take over the kingdom of Mifan, Ran Ran was "kidnapped" by Minister Shen and General Tao to make Chiaotzu order his soldiers to search for the Dragon Balls, tricking him into thinking that it was to wish her back. Lieutenant Blue of the Royal Guard somehow managed to stumble upon her and tried to warn Chiaotzu, but was murdered by General Tao.
At the end of the movie, Tien Shinhan gives Ran Ran back to Chiaotzu.