In House M.D., Remy “Thirteen” Hadley joined House's team in season 4.
Thirteen is played by Olivia Wilde and becomes one of the doctors selected through House's unusual competition to rebuild his diagnostic team. The competition follows the departure of the original fellows and occupies much of the fourth season's early storyline.
Her nickname comes from her contestant number during that selection process. House learns that she has Huntington's disease, a hereditary neurodegenerative disorder, and her family history becomes an important part of her character arc. The diagnosis also shapes her views on privacy, risk, and end-of-life choices.
Thirteen is not the same character as Allison Cameron, Robert Chase, or Eric Foreman, who belonged to the original team. Her arrival marks a major change in the show's ensemble and introduces a doctor with a notably guarded personal life.