"Dancing With The Stars" returns in September for its 21st season, and as always the casting rumors have already started, even though the cast won't officially be announced until Sept. 2 on "Good Morning America." The hit dance show pairs up professional dancers with celebrities and it never fails to keep fans coming back for more each year.

One of the most exciting parts about the show is finding out which celebrities it chooses to compete. Sometimes stars shock us with just how much rhythm they actually have, and other times it can be a little cringe-worthy to watch, but no matter how good or bad they may be, they always seem to be having the times of their lives. As for who will be competing on this upcoming season, nothing has been confirmed yet, but there are quite a few speculations.

Rumors about ABC's most recent "Bachelorette" Kaitlyn Bristowe have been going around, as "DWTS" is known for typically having "Bachelor" or "Bachelorette" contestants as stars on the show. Previous contestants include Chris Soules, Melissa Rycroft, Trista Sutter, Jake Pavelka and Sean Lowe.

A lot of rumors about Caitlyn Jenner joining the cast have also been going around, and a past contestant, who's still in with the ABC family, opened up on his thoughts about these two competing on the show.  

Alfonso Ribeiro, who came out the winner of Season 19, has stayed in touch with producers and doesn't seem to think Jenner is a yes. "I don't think that's going to happen," Ribeiro told E! News. He then added that he "heard" Jenner is "not going to do it."

When asked about Jenner, producer Deena Katz couldn't reveal any information but she did say that she "loves Caitlyn" and "at some point would love to have her on the show," according to Glamour. 

As for contestants that have already been cast, the producers kept their lips sealed. Katz and executive producer Rob Wade said they were almost completely done casting but did not give away any names.

Apparently, ABC has also been negotiating with some specific celebs that they'd love to see dance, according to Gospel Herald. These stars include Amanda Bynes, Amber Rose, Demi Moore (whose daughter Rumer Willis won last season) and Jamie Chung. Other predictions that sites have made based on some rumors they've heard have been Chris Colfer, Ricky Martin, Christie Brinkley, Maureen McCormick, Heather Locklear and Nick Lachey, according to Fashion N Style.

Marilu Henner, known for her role in the '80s sitcom "Taxi," has also speculated on some rumors of her own, according to Realty Today. She was recently on the "Today Show," and when asked about appearing on "DWTS," she candidly said, "We'll see..."

As for people who are definitely not going to be competing, there are unfortunately a few. Katz wanted Ricky Schroder, but he quickly turned the show down, saying that he doesn't dance. Piers Morgan was also asked, but he revealed that he was "too embarrassed to dance."

It seems as though there are plenty of our favorite pros returning to the dance floor, though! Male pros Derek Hough, Tony Dovolani, Mark Ballas, Val Chmerkovskiy, Artem Chigvinstev and Keo Motsepe are all set to come back, according to Fashion N Style. As for female pros, Sharna Burgess, Witney Carson, Allison Holker, Emma Slater and Peta Murgatroyd are all also making a return. Kym Johnson seems to be the only fan favorite who is not certain if she will be returning.

In the meantime, read the rest of what producers Wade and Katz had to say about the upcoming season so far in their very recent interview with Glamour. 

Check back to HNGN for more updates on casting rumors and see who officially gets chosen when the show makes the announcement on Sept. 2 on "Good Morning America!" The season premiere will air on ABC on Sept. 21.

Who would you like to see compete on Season 21?  Comment below!