Momma Mia Hester
Hester Rose Crane, née Palmer (Nancy Marchand in Cheers, Rita Wilson in Frasier) was Martin's wife and Niles and Frasier's mother. By the time the series begins, she has been dead for approximately six years; throughout the course of the series, the cause of her death is never expressly revealed although it is indicated in "Rooms with a View" she died from lung cancer. Hester appears in a dream sequence (experienced by Frasier in "Don Juan In Hell") and in 8 mm cine transferred to video (in the seventh season episode "Mamma Mia" where Rita Wilson also plays Mia Preston who is the spitting image of Hester).

Hester first appeared in a third-season episode of Cheers ("Diane Meets Mom") in which Hester threatened to kill Diane Chambers if Diane did not stop seeing Frasier. Hester at this point was more duplicitous, manipulative and controlling than Frasier's, Niles's and Martin's recollections and descriptions of her later. However, Frasier is surprised by her threats, and says she "has always been the most gentle, rational human being [he] had ever known." Wilson would play a middle-aged version of Hester in the two-part episode "Don Juan in Hell", using prosthetic makeup and a deeper, rougher voice to symbolize a middle point between Wilson's Hester and Marchand's Hester.

Hester was a research psychiatrist and met Martin in 1952 when she was profiling a murderer. She rejected his first marriage proposal, but the two married when she became pregnant with Frasier. Hester had an affair with a family friend when Frasier and Niles were still children, and she and Martin were subsequently separated for a time." A constant theme throughout the series, nonetheless, is that they had a long and healthy marriage.

Hester was the inspiration for both Frasier and Niles to go into the profession. She named her two sons after favorite lab rats. Both her sons take after her more than they do their father, being intellectually pompous, which causes Roz and Martin—especially given her infidelity—to consider that Hester's one-time lab assistant Leland Barton (David Ogden Stiers) might be the boys' biological father. (Without knowing Martin's concerns, Barton reveals he's homosexual, implying he is not their father.) For example, Frasier and Niles quote her as saying "a handshake is as good as a hug." When his snobbish sons embarrass him at "The Timber Mill", a steakhouse chosen by Martin, Martin points out that his wife "may have had fancy tastes, but she had too much class to ever make me or anybody else feel second-rate", and was willing to eat hot dogs and watch ballgames with him.

Hester Crane died in 1987.