Cameron Mathison by Donna Svennevik/ABC; Jennie Garth by Stephen Lovekin/WireImage.com; Wayne Newton by Steve Granitz/Wireimage.com Cameron Mathison by Donna Svennevik/ABC; Jennie Garth by Stephen Lovekin/WireImage.com; Wayne Newton by Steve Granitz/Wireimage.com

Jane Seymour. Floyd Mayweather Jr. Wayne Newton. Jennie Garth. The lineup for the fifth season of ABC's Dancing with the Stars - premiering Sept. 24 - will again showcase actors and singers not known for their dancing, as well as former teen idols, models, athletes, and names many have never heard of. "The people who work best for us have a good story, who come from a field where you think, 'Wow, why are they doing this?'" says executive producer Conrad Green. That includes "Mr. Las Vegas," Wayne Newton, whom producers have been trying to land for two years. "I've worked my entire life doing two shows a night, seven nights a week," says the 65-year-old. "But this is a whole different ball of wax."

The casting may seem arbitrary, but it's a very precise process. Explains Green, "We tend to start by thinking about a few key people we'd love to get on the show, or professions we haven't had. There are certain professions and personality types that the audience really engages with."

Returning pros include Cheryl Burke, Edyta Sliwinska, Kym Johnson, Karina Smirnoff, Tony Dovolani, Jonathan Roberts, Maksim Chmerkovskiy and Julianne Hough. Hough's brother Derek, also a professional dancer, will partner with Garth, who has reached out to 90210 cast mate Ian Ziering - Season 4's fourth-place finisher - for tips. Says Garth, "I'm in the very beginning [stage] where it's very scary because you don't know anything." - Reporting by Deborah Starr Seibel

The Season 5 Stars

" Melanie "Scary Spice" Brown
" Sabrina Bryan ( The Cheetah Girls)
" Helio Castroneves (Indianapolis 500 champion, 2001, 2002)
" Mark Cuban (owner of Dallas Mavericks NBA team)
" Jennie Garth
" Josie Maran, model
" Cameron Mathison ( All My Children)
" Floyd Mayweather Jr., champion boxer
" Wayne Newton
" Marie Osmond, singer and actress
" Albert Reed, model
" Jane Seymour ( Dr. Quinn, Medicine Woman)