The 12 Best Surprise Celebrity Guests on Taylor Swift's '1989' World Tour

Taylor Swift kicked off her 1989 World Tour on May 5, 2015, in Tokyo, Japan – and almost every night thereafter featured some type of magical surprise, a song that wasn’t on the set list – and/or a special celebrity guest.

The stage itself became its own palatial spectacle and featured a catwalk where fans got used to seeing some of the world’s biggest stars join the 26-year-old singer.

From Justin Timberlake to Nick Jonas and Mick Jagger, these are THE 12 best stars who hit the stage with Taylor – in order of when they appeared.

1. Taylor’s “Squad”

Hailee Steinfeld, Lily Aldridge, Gigi Hadid and Lena Dunham (who all happen to be featured in the "Bad Blood" music video) joined Taylor on stage in East Rutherford, NJ on July 10.

2. The Weeknd

The pair, who each scored seven Grammy nominations last week, sang a duet of “I Can’t Feel My Face” in East Rutherford, NJ on July 10.

RELATED: All of Taylor Swift's 1989 World Tour Guests in L.A. -- Ranked by Randomness

3. Nick Jonas

Nick showed up the night after The Weeknd to sing a duet of “Jealous” with Taylor.

4. Lorde

The long-time pals sang “Royals” on July 14 in Washington, D.C.

5. Fifth Harmony

Taylor became an honorary member of the girl group on Aug. 14 in Santa Clara, CA. She donned a matching glitzy blue costume and sang “Worth It” alongside Ally, Camilla, Dinah, Lauren and Normani.

VIDEO: Taylor Swift and Calvin Harris Celebrate Her Birthday Together -- At a Christmas Bash!

6. Kobe Bryant

The Laker legend kicked off Taylor’s five-night stop at the Staples Center on Aug. 21 by presenting her with a special banner to celebrate her record-setting 16 sold-out shows at the arena.

7. Alanis Morissette

Talk about the ultimate break-up songwriter! The rocker queen joined Taylor in L.A. on Aug. 24 and they sang Morissette's “You Oughta Know."

8. Ellen DeGeneres

The daytime talk show host made concert-goers laugh with her sparkly tutu-ensemble as she danced down the catwalk.

9. Lisa Kudrow

Talk about HILARIOUS. The former Friends star sang “Smelly Cat” with the “Wildest Dreams” singer during her final night at Staples Center on Aug. 26.

10. Selena Gomez

Taylor’s BFF showed up on Aug. 26, too. “Swifties” and “Selenators” FREAKED OUT as the long-time besties sang Selena’s hit, “Good For You.”

VIDEO: 12 Signs Selena Gomez and Justin Bieber Could Get Back Together in 2016

11. Justin Timberlake

JT was Taylor’s final guest in L.A. – and what a treat! The twosome sang “Mirrors” – and the performance marked his first since becoming a dad in April.

12. Mick Jagger

The Rolling Stones frontman joined Taylor in Nashville, TN on Sept. 26 for a performance of the rock band’s song, “(I Can't Get No) Satisfaction.”

Taylor’s world tour came to a close last week -- on Dec. 12 in Melbourne, Australia (which was also the day before her 26th birthday). The tour raked in over $250,000,000 dollars and will surely go down in history as one of the most successful of all time.

Who was your favorite surprise guest?! Vote in the comment section or on Twitter by sending @Katie_Krause a tweet with the #ETnow hashtag.

And speaking of 2015 highlights, check out the video below for all the signs Selena Gomez and Justin Bieber could get back together!