Anastacia (born Anastacia Lyn Newkirk on September 17, 1973) is an American singer and songwriter.

She has been highly successful in Europe, Oceania, Asia and South Africa but has not had as much success in her native United States. Despite the lack of American success, she has sold in excess of 30 million albums worldwide.

She is world renowned for her powerful, edgy, soulful voice and is a voice type|dramatic contralto, famous for her ability to hit high notes in her chest voice. Her small stature (160 cm or 5'3") has also led to her being nicknamed "the little lady with the big voice". She is also known for her trademark glasses (often darkly tinted), but she had surgery to correct her vision permanently in August 2005.

She made headlines when she was diagnosed with breast cancer in 2003. In 2007, she married her bodyguard of three years, Wayne Newton, in Mexico.