The late Crocodile Hunter’s hunky, grown-up son, Robert Irwin, has gotten super close with sexy pro dancer Hailey Bills after they hit it off on Dancing With the Stars, but insiders say loved ones fear the 21-year-old Aussie’s taking his eyes off the prize and setting himself up for a heartbreaking fall.

The stars showed up and out for the "Dancing With the Stars" 20th birthday celebration Tuesday night. Mirrorball winners and competitors from past seasons filled the ballroom to honor the dance competition series that has since become a family.

The episode, titled "A 20th Birthday Party," which aired Tuesday, Nov. 11, saw a fan favorite go home and a surprise cameo from Prince William.

Bindi Irwin's daughter Grace, 4, wears an adorable green ballgown to cheer on her uncle Robert Irwin as he performs during 'Dancing with the Stars.'

Guest judge Flava Flav's wild scores kept viewers guessing before a heartbreaking Rock & Roll Hall of Fame Night elimination

As 'Dancing With the Stars' marks 20 years on air, Robert Irwin gets a call from Prince William before sparks fly during his dance with Xochitl Gomez, a past champ.

Wildlife conservationist Robert Irwin earned the first perfect score of the season and received a special message from Prince William.