"Bad Blood" is a song by the American singer-songwriter Taylor Swift from her fifth studio album, 1989 (2014). She wrote the song with the producers Max Martin and Shellback. It is a pop song with hip hop beats and keyboards, and the lyrics are about betrayal by a close friend. A remix featuring the American rapper Kendrick Lamar, with additional lyrics by Lamar and production by Ilya, was released to radio as 1989's fourth single on May 17, 2015, by Big Machine and Republic Records.
Music critics gave the album version of "Bad Blood" mixed reviews; some commented that it demonstrated a new aspect of Swift's artistry, but others criticized the production as bland and the lyrics repetitive. The remix version received somewhat more positive comments for Lamar's verses, featured among the best songs of 2015 on lists by NME and PopMatters, and received a Grammy nomination for Best Pop Duo/Group Performance. Critics have retrospectively considered "Bad Blood" one of Swift's worst songs. The single reached number one and received multi-platinum certifications in Australia, Canada, and the United States.
Directed by Joseph Kahn and produced by Swift, the music video for "Bad Blood" incorporates futuristic and neo-noir elements. The video received extensive media coverage for its ensemble cast consisting of many singers, actresses, and fashion models. It won the Grammy Award for Best Music Video and MTV Video Music Awards for the Video of the Year and Best Collaboration. Swift performed "Bad Blood" on the 1989 World Tour (2015), the Reputation Stadium Tour (2018), and the Eras Tour (2023–2024). Following the 2019 dispute regarding the ownership of Swift's back catalog, she re-recorded both the album version and the Lamar remix for her 2023 re-recorded album 1989 (Taylor's Version); both re-recordings are subtitled "Taylor's Version".
