Mary Cosby

Mary Cosby (born Mary Martha Harris) is a reality TV star best known for her role on The Real Housewives of Salt Lake City. Mary was born and raised in Salt Lake City, Utah, by her mother, Rosalind Cazares.

Before joining reality TV, Mary was known within her church community. She inherited the Faith Temple Pentecostal Church following the passing of her grandmother in 1997. Her position in the church and lifestyle drew attention locally, eventually leading to her casting on Bravo’s The Real Housewives of Salt Lake City alongside Jen Shah, Meredith Marks, Whitney Rose, Heather Gay and Lisa Barlow.

Mary quickly became a standout cast member due to her unique personality and lavish lifestyle. She appeared in the first two seasons as a housewife before stepping away ahead of season 3. She later returned as a friend of the housewives in season 4 and made her full return as a housewife the following season. She went on to appear in season 6, which premiered in September 2025.

Mary has been married to Robert Cosby Sr. since 1998. The marriage was arranged in accordance with her grandmother’s wishes. The couple shared one son, Robert Jr. (born in 2002), who died in 2026.