My Little Pony Crystal Princess: The Runaway Rainbow is a 2006 direct-to-video animated musical fantasy adventure film produced by SD Entertainment and distributed by Paramount Home Entertainment in association with Hasbro. The film is the third feature in the third incarnation of the My Little Pony series and the second film to promote the Crystal Princess line. Unlike The Princess Promenade, the film has been criticized. The DVD also features two more animated features, Greetings from Unicornia and Friends are Never Far Away, which was originally released on video in 2005.

The Runaway Rainbow was made available on hubworld.com (a successor of Hasbro's MonkeyBarTV website), alongside My Little Pony: A Very Minty Christmas and My Little Pony: The Princess Promenade. But they were removed from the site later. The movie has been reissued in the 2-disc DVD collection My Little Pony: Classic Movie Collection, alongside The Princess Promenade, Dancing in the Clouds and Friends are Never Far Away.

Alongside The Princess Promenade and Twinkle Wish Adventure, the film premiered on August 8, 2014 on the Hub Network after its "My Little Pony Mega Mare-athon". According to Broadway World, the "Mega Mare-athon" itself drew in 5.4 million viewers and has earned significant delivery growth on every demographic: Kids 2-11 (+134%), Girls 2-11 (+179%), Kids 6-11 (+169%), Girls 6-11 (+216%), Adults 18-49 (+111%), Women 18-49 (+146%), Adults 25-54 (+74%), Women 25-54 (+76%), Persons 2+ (+124%) and Households (+98%).