Dr. Kelly Benedict was the short-lived replacement fellow for Thirteen hired by Chase in the episode Massage Therapy. She had just finished her residency in psychiatry. She was portrayed by actor Vinessa Shaw.
Lisa Cuddy ordered Gregory House to hire a temporary replacement for Thirteen, and House delegated the task to Chase, mostly to undercut the authority of Eric Foreman. Chase saw that Dr. Benedict had served as an editor for the student newspaper at Rutgers University as an undergraduate and felt that with that experience, she should be able to handle the pressure of working with House. However, Foreman believed that Chase was distracted by Dr. Benedict's looks and only saw a doctor with from a "middling school" with "middling grades".
As such, Chase tried to support Dr. Benedict, while Foreman tried to undercut her, and House spent most of his time trying to figure out the psychological reason why Chase hired Dr. Benedict. House's first theory was that Benedict reminded Chase of Allison Cameron. His next theory was that Benedict reminded Chase of his mother. However, his final theory was just that Chase wanted to sleep with Benedict.
Benedict struggled working on the team, coming up with pedestrian diagnoses in the differential, and finally turned to mental illness to explain the symptoms of the patient, a young married woman. However, in the end, House figured out the problem - the patient was a schizophrenic who was having trouble with her medication. She just needed new pharmacotherapy. He chided Benedict for being a psychiatrist who jumped to the conclusion that it was a mental illness without figuring out that the patient may have already known what was wrong with her and just wouldn't tell the doctors.
However, he left the final decision as to whether Benedict would stay to Chase. Benedict herself suggested she wasn't up to it and Chase decided to let her go, but when she expressed attraction to him, they went out on a date.