Katy Perry vs. Taylor Swift — Bad Blood

Taylor wrote "Bad Blood" about Katy (confirmed in interviews) after Perry allegedly poached her backup dancers mid-tour. The song hit #1 and won a Grammy. The music video featured a dozen celebrity cameos and 1.3 billion YouTube views. Perry responded with "Swish Swish" (which flopped comparatively at 400 million views). The feud ended in 2019 when Perry sent Taylor a literal olive branch and they hugged in a burger costume at the VMAs. The reconciliation was wholesome. The "Bad Blood" royalties ($25+ million) were better. Sometimes peace is more expensive than war.