Dr. Bennett was the endocrinologist on call during the time period of the Season 3 episode Insensitive. He was an unseen character.
House wanted to interrupt Cuddy's date with Don so went he went to her house on the pretense he needed a consult. She reminded him that Dr. Bennett was the endocrinologist he was supposed to call in such circumstances. She then shot down his diagnosis. However, House's visit had the desired effect - Don realized that Cuddy really liked House and that she could never like him like that.