Everyone -- and we do mean nearly everyone -- has seemingly dropped by this time around, from besties like Selena Gomez to newcomers such as Andy Grammer. (For the record, we're only counting guests who actually performed with Swift, not just people who walked the runway.)
But even among all the special guests, there have been some seriously surprising ones, even by Swift's own be-prepared-for-anything standards.
Five of the most surprising -- but delightful -- tour guests so far are below.
1. Uzo Aduba
The Orange in the New Black fave surprised fans with a pitch-perfect throwback of Fearless standout "White Horse" in Los Angeles Aug. 22.
2. Avril Lavigne
What Bad Blood? After the Internet stirred up rumors that Lavigne wasn't the biggest fan of Swift, Swift herself put the silly rumors to bed, inviting an ecstatic Avril on stage to duet. Nothing "complicated" about that.
3. Lisa Kudrow
In hindsight, perhaps we should have seen this coming. After all, Swift self-identifies as a huge Friends fan. But it was still an unexpected treat to see Swift joined by the once and future Phoebe Buffay (Lisa Kudrow) for the classic Friends jingle "Smelly Cat."
4. Mick Jagger
File under: Things we never thought we'd see. Taylor Swift shaking her hips and singing along to "Satisfaction" on Sept. 24.
5. Steven Tyler
Swift got in touch with her inner hard-living rockstar (how very 1989, indeed!), duetting with Tyler to "I Don't Want to Miss a Thing" in Nashville Sept. 25.
Who is your pick for Taylor Swift's most surprising 1989 tour guest so far?