John Gregg was born 1668 in Ardmore, County Waterford, Ireland to William Gregg (1642-1687) and Ann (?-?) and died March 1737 Wilmington, New Castle County, Delaware, United States of unspecified causes. He married Elizabeth Cooke (1673-?) 1 November 1694 in Concord Friend's Meeting, Concord Township, Chester County, Pennsylvania, United States.
John Gregg was born in 1668 in Ardmore County, Waterford, Ireland. He was was 14 years old when he left Ireland and settled in Delaware. He was a Quaker.
John was 19 years old when his father died. His family continued to live in the family home and kept possession of their land. John was a serious, proud and capable youth. He was always a faithful Friend and a busy person. In the summer of 1694, when 26 years old, he built a two-story stone house and married Elizabeth Cooke at Concord Friend's Meeting on November 11, 1694.
On August 17, 1702, John and Elizabeth bought more land and erected a Grist Mill. At one time, John owned 5,700 acres of fine land along the Brandywine River. John Gregg had seven children (3 daughters and 4 sons).
John Gregg of Christiana Hundred, New Castle County, yeoman, aged about 67 years, made a disposition about 1735 'that he has dwelt in said County about 51 yrs.'"
His will is dated April 27 in Wimington, New Castle, Delaware.
Children
| Name | Birth | Death | Joined with |
| Thomas Gregg (1688-1748) | 1688 New Castle County, Delaware, United States | 1 September 1748 Kennett, Chester County, Pennsylvania, United States | Dinah Harlan (1707-1763) |
| William Gregg (1695-1747) | |||
| Amy Gregg (1700-1738) | |||
| Samuel Gregg (1710-?) | |||
| Joseph Gregg (1710-1770) | |||