| Surname | Country | State | County or Province | From | To | Member |
|---|---|---|---|---|---|---|
| Iller | Switzerland | Appenzell | Speicher | 1750 | 1790 | B018-1 |
| Imyak | I002-1 | |||||
| Inglesby | Ireland | County Meath | Trim | 1814 | 1850 | O006-1 |
| Irion | USA | Ohio | 1820 | 1880 | D005-1 | |
| Irion | USA | Iowa | 1820 | 1880 | D005-1 | |
| Irion | USA | Nebraska | Ida County | 1820 | 1880 | D005-1 |
| Irion | USA | Nebraska | Holt County | 1820 | 1880 | D005-1 |
| Irion | USA | Nebraska | Warren County | 1820 | 1880 | D005-1 |
| Irion | USA | Oklahoma | Pottawottamie County | D005-1 | ||
| Isabelle | France | B026-1 | ||||
| Isabelle | Canada | Quebec | B026-1 | |||
| Isabelle | USA | New Hampshire | Hillsborough County/Manchester | B026-1 |