<P> Early in the series, Carter's plots typically stayed in the realm of the ER . In a symbolic gesture of this transference, he was told by Mark Greene "you set the tone" on Dr Greene's last day in the ER . Dr. Greene had been told the same thing, by Dr. Morgenstern, in the pilot episode in Season 1 of the show . Dr. Carter, in turn, said the same thing to Dr. Archie Morris as Carter left the ER, although Morris did not understand the significance . </P> <P> Throughout the course of the series (particularly at the beginning of Season 8) we meet various members of Carter's wealthy family and see how he is very uncomfortable being an upper - class young man, to the point where he goes out of his way to not talk about his background . </P> <P> His father, John (Jack) Truman Carter Jr . (Michael Gross) is caring but stiff, and very acquiescent with his wife until he gets tired of her being an "emotional vampire" and divorces her . He and Carter have an awkward relationship where they love each other but John doesn't respect his father . Jack recognizes this and keeps some distance from him as a result of it . Carter's mother, Eleanor (Mary McDonnell), is emotionally distant and cold . Her personality was largely shaped because she blamed herself for Carter's older brother, Robert's death from leukemia . Carter eventually figures out that much of her sadness comes from this and they briefly become closer, but eventually Eleanor removes herself from any ties to her family after Jack divorces her, to the point where John has no idea how to reach her and she refuses to return a phone call he makes after Millicent Carter (who hated her) passes away . </P> <P> Carter's grandfather, John Truman Carter Sr. (George Plimpton), is the most disappointed by Carter's career choice, and though Carter respects him, he also resents him for that . Carter's grandmother, Millicent Carter (Frances Sternhagen), is a benefactor of the hospital, even funding Carol Hathaway's clinic . Carter is very close to his grandmother (whom he calls "Gamma") and intermittently lives at her home . They do occasionally argue, however, usually in regard to Carter's reluctance to participate in matters related to the family foundation; Gamma modifies her will to remove Jack as the head of the foundation and puts John in charge of it, leading to him changing its mission from supporting Chicago arts programs to supporting public health initiatives . </P>

Who played john carter's mother on er