Hamill, 56, made the announcement at the end of the episode just before the season's first celebrity was to be eliminated from the competition.
"I've taken the advice of my spine surgeon and I need to withdraw from the competition. I have an injury that could be irreparable and nerve damage and it would be completely unfair for me to stay in this and have any of these people go home. I can't do what I need to," Hamill said, her voice shaking, as her professional dance partner Tristan MacManus stood by her side. "I wish I could give it my all, but I can't."
Still in the running for the coveted mirror ball trophy, along with their professional dance partners, are singers Kellie Pickler and Wynonna Judd, comedians Andy Dick and D.L. Hughley, boxer Victor Ortiz, soap star Ingo Rademacher, Disney Channel star Zendaya Coleman, reality TV personality Lisa Vanderpump, Olympic gymnast Aly Raisman and NFL star Jacoby Jones.