Dr. Judith Barnett was a psychiatrist that worked for the CIA. Although she was highly accomplished and had an ivy league education, she came to the CIA because she wanted to serve her country (After Six).
She met with several of their field operatives to discuss the psychology repercussion of their work as well as problems in their personal lives. Her patients included Sydney Bristow, Michael Vaughn, Jack Bristow, Arvin Sloane, and Marcus Dixon. She had a very brief affair with Sloane.
Season 1
After he learned that Sydney's mother killed his agent father, Vaughn received orders to visit a CIA psychiatrist - Dr. Barnett. Barnett questioned whether his relationship with Sydney was appropriate (The Box, Part 1).
When Jack Bristow learned that Irina was still alive, Arthur Devlin ordered him to speak with Dr. Barnett. She was a shrewd judge of Jack's character; she did not believe that he was being truthful with her or himself and asked to see him once a week (Masquerade).
Season 2
Sydney meets frequently with Dr. Barnett to discuss her mother (The Enemy Walks In).
Following the death of his wife and at Vaughn's prompting, Dixon saw Dr. Barnett to discuss his excessive violence on the job and his use of painkillers. When Dixon manipulated the results of his drug text, Sydney lied to Dr. Barnett to cover for him (Countdown).
Season 3
Arvin Sloane met with Dr. Barnett in Zurich, on Jack's recommendation, to discuss his residual depression over the death of his wife (After Six). He was extremely rude in their fist meeting, but later apologized and asked her to dinner.
She agreed as he was the subject of one of her papers. At dinner, she tried to compliment his transformation from criminal to humanitarian, but he again insulted her and she stormed out. When he tried to diffuse the situation, he also admitted that he once had an affair with Sydney's mother and believed he could possibly be her real father (Blowback). Sloane and Barnett began an intimate affair (Façade), but it turned sour when he used her office computer to help Sark escape CIA custody and kidnap Dixon's children (Taken).
Vaughn met with Dr. Barnett to discuss his issues with his wife (Hourglass).