Thomas Barnes III was born 23 March 1662 in Marlborough, Middlesex County, Massachusetts to Thomas Barnes (1636-1679) and Abigail Goodenow (1642-1678) and died 23 April 1734 Brookfield, Worcester County, Massachusetts of unspecified causes. He married Mary Howe (1665-1719) 14 April 1685 in Marlborough, Middlesex County, Massachusetts.
Children
| Name | Birth | Death | Joined with |
| Samuel Barnes (1686-1733) | |||
| Martha Barnes (1686-1746) | |||
| Prudence Barnes (1689-1770) | |||
| Obadiah Barnes (1691-1732) | |||
| Lydia Barnes (1692-1778) | |||
| Comfort Barnes (1602-1747 | |||
Siblings
| Name | Birth | Death | Joined with |
| Thomas Barnes (1662-1734) | 23 March 1662 Marlborough, Middlesex County, Massachusetts | 23 April 1734 Brookfield, Worcester County, Massachusetts | Mary Howe (1665-1719) |
| Dorothy Barnes (1664-1686) | |||
| John Barnes (1666-1752) | 25 December 1666 Marlborough, Middlesex County, Massachusetts | 5 April 1752 Marlborough, Middlesex County, Massachusetts | Hannah Howe (1677-1742) |
| William Barnes (1669-1731) | |||
| Abigail Barnes (1671-1749) | |||
| Theophilus Barnes (1673-1675) | |||
| Susanna Barnes (1676-1712) | 2 February 1676 Marlborough, Middlesex County, Massachusetts | 15 January 1712 Marlborough, Middlesex County, Massachusetts | Supply Weeks (1671-1755) |