Tom Larkin is the younger brother of Maryellen Larkin.
- Name: Tom Larkin
- First Appearance: The One and Only
- Stan Larkin: Father
- Kay Larkin: Mother
- Joan Larkin: Oldest sister
- Carolyn Larkin: Older sister
- Maryellen Larkin: Older sister
- Beverly Larkin: Older sister
- Mikey Larkin: Younger brother.
- Grandpop: Maternal grandfather
- Grandmom: Maternal grandmother
- Jerry Ross: Brother-in-law
Tom is four years old at the start of the series. Maryellen says he often looks like a cheerful dandelion, due to his blond hair, and is always happy.