Kate Donnelly is the ex-wife of Charlie Donnelly, the mother of Ned Donnelly, Elyse Keaton, and Michelle, and the grandmother of Alex, Mallory, Jennifer, and Andrew.
Kate and Charlie were married circa 1943 or 1944. They were happy for many of the next four decades, but gradually grew apart.
Kate was a loving and attentive mother. When Elyse was seven, she had chickenpox, and Kate made her feel better by making a cave out of blankets and pillows, calling it Donnelly Island, and pretending they were castaways in the South Pacific.[1]
When Elyse was fifteen, Kate told her, "A young lady always says 'please' and 'thank you,' she always laughs at a young man's jokes, and a young lady never beats a boy in sports."[2] As of No Nukes is Good Nukes, her views on gender roles seem to have become more liberal.
Kate loves cooking but is extremely bad at it. Her family tries to find excuses not to eat her food, which is borderline inedible.
Kate disagrees with Elyse's political views but admires her willingness to stand up for them. After Elyse and Steven are arrested in No Nukes is Good Nukes, Kate and Jennifer bring them Thanksgiving dinner in jail and are only joined later by the rest of the family.
In M is for the Many Things, we learn that Kate and Charlie are separated, have almost finalized their divorce, and have sold their house. Kate has started a relationship with Philip Morgan, who was her dentist for almost twenty years, much to Elyse's horror. Kate and Philip go to a concert, get ice cream, sit in a sauna, and spend the night together at Philip's house. Elyse tries to stop Kate from seeing Philip, but Kate reminds Elyse that she is a mature adult capable of making her own decisions and that she used to have the same arguments with Elyse when Elyse was in her late teens.
As of Cold Storage, Kate lives near Leonard and Marge. Her new house has cable TV. She takes care of Andrew Keaton while the rest of the Keaton family is in England during Family Ties Vacation.