Ginny is Sam Truman's ex-wife. She is only mentioned in two episodes and does not appear in the series.
Will describes Ginny as "morose, controlling, and icy". Will's dislike of Ginny is the main cause for the estrangement between him and his brother, which is explored in Big Brother is Coming. She separates with Sam during the first season, and in the eighth season Sam reveals that they divorced because she was having an affair with someone "who has a brokerage firm in Pelham" and "used to be [his] best friend".