Jonathan Roberts, Charlotte Jørgensen, Edyta Sliwinska, Ahly Costa & Louis Van Amstel
All six original pros from season one—inlcuding Alec Mazo—returned for the show's birthday. In fact, they opened the episode with moves that proved they've still got what it takes to dance to the top.
Apolo Anton Ohno & Rashad Jennings
The Olympic speed skater (season 4 winner and season 15 contestant) was Jordan Chiles' partner in the relay dance against Elaine Hendrix and her guest partner, NFL alum and season 24 winner Rashad.
Xochitl Gomez & Joey Graziadei
Season 32 winner Xochitl partnered with Robert Irwin against Alix Earle and her partner, season 33 winner Joey for the relay dance.
Rumer Willis & Kaitlyn Bristowe
Rumer (season 20 winner) partnered with Dylan Eforn in the relay dance against Andy Richter and Kaitlyn (season 29 winner).
Kenya Moore
The Real Housewives of Atlanta star returned to the ballroom after competing on season 30 with Brandon Armstrong.
Chandler Kinney
The Disney Channel star, also partnered with Brandon, returned after placing 3rd in season 33.
Daniel Durant, Ilona Maher & Marlee Matlin
The season 31, season 33 and season 6 alums struck a pose together on the event's red carpet.
Kelsey Anderson
The Bachelor alum was there in support of her fiancé Joey as he hit the stage with Alix.
Sabrina Bryan
The Cheetah Girls star returned to the ballroom 18 years after she competed on season 5, before going on to compete in the all-stars 15th season.
Kristi Yamaguchi
The former champion smiled wide upon her return to the ballroom after skating to the top during season 6.
Charity Lawson
The Bachelorette alum—and season 32 contestant—was a vision in gold on the red carpet.
Lindsay Arnold
The former pro—who last competed during season 30—returned to the ballroom.
Stephen Nedoroscik
The Olympian was all smiles during his return after flipping his way to fourth during season 33 with partner Rylee Arnold.
Bill Nye
The science guy returned to the ballroom 12 years after he became the dancing guy during season 17.
Jenn Tran
The Bachelorette alum, who placed 7th alongside partner Sasha Farber during season 33, struck a pose.
Chrishelle Strause
The Selling Sunset star returned after finishing in 8th during season 29 with partner Gleb Savchenko.
Ariana Madix
The Love Island USA host showed off her new darker hair while returning after placing 3rd with Pasha Pashkov in season 32.
Scott Hoying & Sasha Farber
The season 34 contestant, who was eliminated alongside Rylee, struck a pose with the former pro.
Amanda Kloots
The 4th place finisher from season 30 returned to cheer on her former pro partner Alan Bersten.