Kay Larkin is the mother of Maryellen Larkin, she refers to her as "Mom."
- Name: Kay Larkin
- First Appearance: The One and Only
- Stan Larkin: Husband
- Joan Larkin: Eldest daughter
- Carolyn Larkin: Elder daughter
- Maryellen Larkin: Younger daughter.
- Beverly Larkin: Youngest daughter.
- Tom Larkin: Older son.
- Mikey Larkin: Younger son.
- Grandpop: Father
- Grandmom: Mother
- Jerry Ross: Son-in-law
Kay is a stay-at-home mother as many women were in the 1950s. She is from Georgia and often tells Maryellen stories from when she was a girl. Kay married Stan during the Great Depression. She's quite frugal and crafty, but not very good at sewing.
With the burdens of six kids (four of them being under ten until Maryellen's birthday) she becomes frequently frazzled and upset. While she does tend to the house and family well, there are multiple signs that she gets annoyed with the social expectations of the perfect household and what she's expected to handle as a stay at home mother. (An example is when Stan buys the trailer without informing her, then shows her the ironing board and kitchen in delight to which she replies with noted sarcasm.) She frequently becomes impatient with Maryellen, but understands her daughter's problems with being the middle child and how she feels overlooked and immature.
During WWII (before Maryellen was born) she worked as a line manager in an aircraft factory; she discusses that she could have kept the job but declined when she saw so many women being laid off to reopen jobs for the returning men.