But Swift had everyone talking ahead of the release of her GRAMMY-winning 1989 album, thanks to her quotes to Rolling Stone magazine, in which she revealed that she had a feud with a fellow pop star, which inspired her hit song, "Bad Blood."
"For years, I was never sure if we were friends or not," Swift said. "She would come up to me at awards shows and say something and walk away, and I would think, 'Are we friends, or did she just give me the harshest insult of my life?'"
"She did something so horrible," she continued. "I was like, 'Oh, we're just straight-up enemies.' And it wasn't even about a guy! It had to do with business. She basically tried to sabotage an entire arena tour. She tried to hire a bunch of people out from under me.”
Several internet commenters then noted that Perry did lure a few backup dancers away from Swift's tour as she embarked on her own Prismatic tour in 2014. However, according to one of the dancer's agents, the dancers "exercised a 30-day out in their contracts and left Taylor, but Katy didn't steal them."
"They just didn't want to tour with her anymore because there is basically no choreography or dancing in her show," the agent claimed.
While Swift did say that the feud had nothing to do with a boy, both previously dated singer John Mayer.
Sept. 9, 2014: Katy Perry Calls Swift a 'Mean Girl'
Watch out for the Regina George in sheep's clothing...
"If somebody is trying to defame my character, you're going to hear about it," Perry told Billboard magazine when asked if her tweet was about the "Shake It Off" singer.
May 23, 2015: Taylor Swift Will Never, Ever Talk About Katy Perry Again
In an interview with The Telegraph, Swift made it clear she was over Perry. "I'm not giving them anything to write about," she said when asked about about her nemesis. "I'm never going to talk about her in my interview. It's not going to happen."
Swift did, however, confirm she had her "enemies" in the business. "It's not real if someone appears to never have any issues with anyone," she explained. "I have my friends. I have enemies."
July 22, 2015: Katy Perry Hits Back at Taylor Swift Amid Her Nicki Minaj Beef
Finding it ironic to parade the pit women against other women argument about as one unmeasurably capitalizes on the take down of a woman...
"If I was a different 'kind' of artist, 'Anaconda' would be nominated for best choreo and vid of the year as well," Minaj tweeted, getting vocal about her VMA snub. “If your video celebrates women with very slim bodies, you will be nominated for vid of the year."
Swift took the tweet personally, responding, “I've done nothing but love and support you. It's unlike you to pit women against each other.”
Perry then chimed in with a devastating tweet referencing "Bad Blood."
"Finding it ironic to parade the pit women against other women argument about as one unmeasurably capitalizes on the take down of a woman..." she wrote.
July 27, 2015: Taylor Swift Throws 'Left Shark' Shade at Katy Perry
Swift appeared to be back at it again later that month, seemingly trolling Perry during her Foxborough, Massachusetts, stop as part of her 1989 world tour. Her performance of "Bad Blood" curiously featured a cameo from a life-sized shark mascot -- a not-so-thinly veiled dig at Perry's Super Bowl dancer-turned-internet meme.
July 13, 2016: Calvin Harris Brings Taylor Swift and Katy Perry's Feud to the Forefront
Swift's ex-boyfriend, Calvin Harris, brought up Swift and Perry's bad blood when he slammed the singer on Twitter. Harris was upset after Swift's rep confirmed that the singer wrote his and Rihanna's summer hit, "This Is What You Came For," under the pseudonym Nils Sjoberg -- when the two were still a couple -- and after Swift began dating actor Tom Hiddleston, who she broke up with that same year.
"Hurtful to me at this point that her and her team would go so far out of their way to try and make ME look bad at this stage though," he tweeted, after initially praising Swift. "I figure if you're happy in your new relationship you should focus on that instead of trying to tear your ex bf down for something to do."
"I know you're off tour and you need someone new to try and bury like Katy ETC but I'm not that guy, sorry. I won't allow it," he continued.
Perry later tweeted out a GIF of Hillary Clinton shooting out an epic "I told you so"-look shortly afterward.
Adding more fuel to the fire, Perry then retweeted her own tweet from May 2015, where she wrote, "Time, the ultimate truth teller."
Sept. 10, 2016: Katy Perry Would Collaborate With Taylor Swift Under One Condition
Perry was looking for an apology after a fan asked her on Twitter: "Will you ever collab with Taylor Swift?"
She surprisingly tweeted back: "If she says sorry, sure!"
Oct. 26, 2016: Katy Perry Rocks Out to Kanye West's 'Famous' Taylor Swift Diss
Perry once again rekindled the pop star feud while celebrating her 32nd birthday at Kanye West's concert in Inglewood, California. She even shared a video of herself dancing along to the rapper's now infamous Swift diss in "Famous."
May 20, 2017: Katy Perry Calls "Swish, Swish" an 'Anthem' Against Bullying
Though Perry never mentions Swift in her song, "Swish, Swish," the track is clearly slamming somebody, and of course, fans couldn't help but notice that that "swish" isn't so far off from Swift.
"From a selfish or a sheep/ Don't you come for me/ No, not today/ You're calculated/ I got your number," Perry sings. "'Cause you're a joker/ And I'm a courtside killer queen/ And you will kiss the ring/ You best believe."
"So keep calm, honey, I'ma stick around/ For more than a minute, get used to it," she continues. "Funny my name keeps comin' outcho mouth/ 'Cause I stay winning."
"I think it's a great anthem for people to use whenever someone's trying to hold you down or bully you," Perry told Jimmy Fallon about the song during her appearance on The Tonight Show. "That's kind of what this record is about. It's just like [a] 360-degree liberation. ... I think 'Swish' represents the liberation from all the negative that doesn’t serve you."
Of course, some of Swift's pals definitely didn't see it that way. Ruby Rose took to Twitter to defend Swift and slammed Perry, writing: "Purposeful poop" to 'bomb a petit' to a sloppy mess of writing over the top of Funkagenda..stop trying to make 'Wit..I mean 'fetch' happen."
"I've always stood up for the people I love and against things I think are cheap or mean spirited. That's not new. You have to follow your ❤," the actress continued. "I just think with everything going on in the world to go from rebranding as political activist only to ditch it and go low.. is.. a bummer."
May 22, 2017: Katy Perry Claims Taylor Swift 'Started' Their Feud and 'It's Time for Her to Finish It'
"Honestly, it's really like she started it and it's time for her to finish it," Perry said after the Late Late Show host asked her to clear things up. "She wouldn't speak to me. I do the right thing any time that it feels like a fumble. It was a full shut-down and then she writes a song about me and I'm like, 'OK, cool, cool, cool. That's how you wanna deal with it?'"
"But, what I wanna say is that I'm ready for that B.S. to be done," she added. "Now, there is the law of cause and effect. You do something and there's going to be a reaction. And trust me, Daddy, there's going to be a reaction. It's all about karma."
It should be noted that "Swish Swish," coincidentally, has a line about karma, where Perry croons, "Karma's not a liar."
June 8, 2017: Katy Perry Slams Taylor Swift for 'Trying to Assassinate' Her Character
Perry wasn't quite done talking about Swift. In an interview with NME, she gave background on why she decided to address the feud with Corden.
“I mean, I’m not Buddha -- things irritate me,” she said. “I wish that I could turn the other cheek every single time, but I’m also not a pushover, you know? Especially when someone tries to assassinate my character with little girls [her fans]. That’s so messed up!”
June 8, 2017: Taylor Swift Puts Entire Song Catalog Back on Streaming Services -- Right When Katy Perry's Album Drops
Actions speak louder than words. Though Swift has stayed silent on Perry's comments about her, she announced on June 8, 2017 that her entire song catalog would return to all streaming services at midnight -- just when Perry's Witness album dropped.
Perry was later asked about whether the move bothered her during an interview with the Today show's Natalie Morales. "I don't know, I can only do me," Perry replied. "All I need to say to her is I love her, and God bless her on her journey. And that’s it."
June 10, 2017: Katy Perry Is '100 percent' Ready to 'Let Go' of Feud
Perry made it clear that she was ready to make amends with Swift during a conversation with Arianna Huffington, which was live streamed to promote Witness.
"I'm ready to let it go. Absolutely, 100 percent," Perry said of the longtime beef. "I forgive her, and I'm sorry for anything I ever did, and I hope the same from her, and I think it's actually... I think it's time."
"There are bigger fish to fry, and there are bigger problems in the world," she continued. "I love her and I want the best for her, and I think she's a fantastic songwriter, and like, I think that if we both, her and I, can be representatives of strong women that come together despite their differences, I think the whole world is going to go, like, 'Yeah, we can do this.' Maybe I don't agree with everything she does, and maybe she doesn't agree with everything I do, but like, I just... I really, truly, want to come together, and in a place of love and forgiveness, and understanding and compassion."
June 12, 2017: Katy Perry Changes a Key 'Swish, Swish' Lyric
Perry backed up her conciliatory quotes by pointedly changing a few lyrics while singing "Swish Swish" during an outdoor concert for her fans. Instead of singing the line, "Don't you come for me," in the first verse, Perry sang, "God bless you on your journey, oh baby girl."
July 19, 2017: Katy Perry Says She's 'Always Loved' Taylor Swift Despite Their 'Differences'
Perry wasn't done trying to make nice with Swift.
In an interview on Australia's Today show, Perry reiterated that she had love for the singer. "I mean, I love her, I always have," Perry told host Richard Wilkins. "We've had our differences, but I just continue to say, 'God bless her on her journey.'"
However, Swift did not end up attending the 2017 VMAs.
August 24, 2017: Katy Perry Releases Star-Studded "Swish, Swish" Music Video
Like Swift's "Bad Blood" music video, Perry enlisted a bunch of celebrities to star in the music video for her single, "Swish, Swish," her diss track widely speculated to be about her frenemy. The release was ahead of Swift dropping her first single, "Look What You Made Me Do," off her album, Reputation.
August 24, 2017: Taylor Swift Releases Shady "Look What You Made Me Do" Music Video
While Perry hosted the VMAs, it was Swift that got people talking with her shade-tastic music video for "LWYMMD."
Main moments of shade include Swift made up in a way that could be described as “Katy Perry-esque” and wrecking a car (complete with a Katy-cat in the front seat).
March 17, 2018: Karlie Kloss Addresses Taylor Swift Feud Rumors After Hanging Out With Katy Perry
During a montage segment of Idol hopefuls auditioning for the panel, Perry's fellow judge, Luke Bryan, asked one scruffy, guitar-carrying singer, who he looks up to as a musical artist. "I'm sorry for this Katy… Taylor Swift," the hopeful answered nervously.
"Oh, you don't have to be sorry," Perry replied.
"I love Taylor Swift," the contestant added, emphatically.
Will these two ever make amends? Here's more on the feud:
May 8, 2018: Katy Perry Sends Taylor Swift a Literal Olive Branch:
It appears the feud is finally over. Swift shared a video of an olive branch and a note from Perry on her Instagram Stories on May 8, one night before her Reputation tour kicked off. The note is addressed "Hey Old Friend," and a closer look at the handwriting shows that Perry apologized to Swift.
"Hey old friend, I've been doing some reflecting on past miscommunications and the feelings between us, I really want to clear the air," the note reads.
Swift was clearly pleased by the gesture.
"So, I just got back to my dressing room and found this actual olive branch," she says in the video. "This means so much to me."
"Thank you Katy," the text on the video also reads, along with pink heart emojis.
“Katy planned a very personal, sweet apology and took time to write a kind note in hopes Taylor would see how much she cared about putting this behind them,” the source said. “Katy told friends if Taylor didn't accept this apology, she would keep trying because she is done holding on to the past and wants to be part of the change in today's society. She wants to set a good example for women, so she planned to never give up, if that is what it took."
“Katy hopes they finally can be supportive of each other's music and maybe one day soon even hang out together again," the source added. "Katy realizes they need to take it one day at a time, but that this is a great start.”