Marilyn Truman, Will's mother, played by Blythe Danner. A typical WASP, Marilyn regularly drinks, collects Lladró statues and treats them as if they were her children, and put up with her husband's regular affairs until their ultimate separation. She is not a fan of musical theater - once claiming that Les Misérables was unrealistic because "poor people don't sing that much" - but was impressed with Mamma Mia!. She does not like the jokes Grace and Karen make about Will's sexuality saying, "Is that a gay joke? I don't like that."

George Truman, Will's father, played by Sydney Pollack. He had trouble dealing with telling others of his son's sexuality, initially telling his friends Will was married to Grace. He died in season 8, only days after having a fight with Will in which he admitted he would rather Will wasn't gay.

Sam Truman, Will's brother, played by John Slattery in season one and Steven Weber in season 8. He had a falling-out with Will over comments Will made about his wife, but reconciled after he had a one-night stand with Grace.

Jordan Truman, Sam's adopted son and Will's nephew, played by Reed Alexander. Clearly gay, Jordan incenses Will since Marilyn is incredibly accepting of him even though she was not at first accepting of Will.

Paul Truman, Will's brother, played by Jon Tenney. Paul has never really come to terms with his brother's sexuality.

Peggy Truman, Paul's wife and Will's sister-in-law, played by Helen Slater.

Tina, played by Lesley Ann Warren. George's mistress, she began a relationship with him while he was still married to Marilyn, but was ultimately dismayed to learn that George was then seeing his ex-wife behind her back.