Taylor Swift usually wrote her songs on her own, with the exception with a couple of her songs like Everything Has Changed, with Ed Sheeran and The Last Time, with Gary Lightboy. Bad Blood proved to have not made that list, until the music video was released.
She teamed up with rapper Kendrick Lamar to create the hit video. It was aired on the Billboard Music Awards, so lots of people were able to view it.
Lots of celebrities starred in Bad Blood, including Taylor Swift (duh!), Kendrick Lamar (duh!), Selena Gomez, Ellie Goulding, and Zendaya, with lots of others you may know.