Bad Blood: Katy Perry and Taylor Swift

Before they patched things up with a literal olive branch, Taylor and Katy were locked in an absolute cold war over stadium tour personnel. Swift claimed Perry tried to systematically sabotage an entire tour by poaching her core backing dancers right from under her feet. Explaining why she penned the lethal track Bad Blood, Taylor told Rolling Stone in an interview published on 8 September 2014: "She basically tried to sabotage an entire arena tour. She tried to hire a bunch of people out from under me ... So now I have to avoid her."