Maria Palko is the wife of Bob Palko, the patient in the Season 2 episode Clueless. She's portrayed by actress Samantha Mathis
While Maria and Bob were role-playing a rape fantasy, he started choking and turning blue. Maria called 911 and Bob was taken to Princeton-Plainsboro Teaching Hospital where she became quickly frustrated by the failure of the doctors to reach a diagnosis. The case was soon assigned to Gregory House.
While Allison Cameron was taking a medical history, the couple was very forthcoming with details about their sex life. Maria remained constantly at Bob's side and criticized many of the doctors' guesses.
However, despite the "happy couple" talk, House can't get over the fact that they rule out all the possible diagnoses and the only possible source of anything that could be harmful to Bob is his wife, who is constantly in his environment. House confronts her about the possibility of poisoning Bob, but she allows him to search her possessions. However, she won't allow a body search and Lisa Cuddy won't allow it. Everyone other than House won't believe it because she seems devoted.
However, House figures out Bob is being poisoned with gold. He rushes to his house to obtain some stannous chloride and instructs his team not to let Maria go to the washroom. He finally catches her and her hands are stained with gold compounds that are revealed by the stannous chloride, which reacts with gold and stains her fingers purple. She is arrested and jailed for her crimes.
The reasons behind her actions are never revealed.