Surname G
| SURNAME | TOWNSHIP | RESEARCHER |
| Gabriel | Verdell Leikam | |
| Gail | Waukegan | Michael Gail |
| Gallegos | Waukegan | Roy Gallegos |
| Garrett | Patti Fellows | |
| Garrity | Highwood, Highland Park, Deerfield Twps.; mid to late 1800s | Bridget |
| Garrity | Highwood, Highland Park, Deerfield Twps.; 1837 to present | Bridget |
| Gavigan | Pat Gavigan | |
| Geary | Andrew Pavlin | |
| Geary | Julie Fedde | |
| Geary | Wauconda | Roger Peterson |
| Gehrke | Marilynn Wienke | |
| Geist | Mundelein | R. Goetz |
| Geraghty | Candie Hirak-Horrell | |
| Gerry | K. Don Thompson | |
| Gibbons | Waukegan? | Gerald G. Gibbons |
| Gillett | Max G. & Donna Kearse | |
| Gloden | Verdell Leikam | |
| Glynch | Wauconda | Roger Peterson |
| Golding | Waukegan, 1891-1935 | Penny Stanley |
| Goodrode | Highwood | Perennials@aol.com |
| Gould | Fremont & Waukegan | Cathy Sheehan |
| Grable⁄Grableaux⁄Grabel | Wadsworth -- 1850s | Grace Radtke |
| Grady | Ruth Streed Filstead | |
| Graper⁄Graeper | Antioch | Denise Parsons |
| Gray⁄Grey | Shields Twp., 1836; Libertyville | Catherine Green |
| Green | Wauconda | Joe Bagg |
| Gridley | Vernon | Toni Mann |
| Griffin | Benton & Newport | John R. Griffin |
| Griffin | Sophia Preston | |
| Grimes | Waukegan | Annie Schaff |
| Griswold | McHenry & Lake Co. | Carl Kellogg |
| Grube | Antioch | Denise Parsons |
| Gunsaullus | Grant | Wilda Marshall Brown |
| Guthrie | Zion 1920-Present | Nancy Cheesbrough |