Identifiers: city · CDP · borough
| Rank | Community | Population |
|---|---|---|
| 1 | New London (city), CT | 27,367 |
| 2 | Groton (city), CT | 9,387 |
| 3 | Branford Center (CDP), CT | 6,026 |
| 4 | Long Hill (CDP), CT | 3,948 |
| 5 | Clinton (CDP), CT | 3,441 |
| 6 | Niantic (CDP), CT | 3,194 |
| 7 | Waterford (CDP), CT | 3,074 |
| 8 | Oxoboxo River (CDP), CT | 2,955 |
| 9 | Deep River Center (CDP), CT | 2,765 |
| 10 | Guilford Center (CDP), CT | 2,586 |
| 11 | Essex Village (CDP), CT | 2,583 |
| 12 | Old Saybrook Center (CDP), CT | 2,278 |
| 13 | Madison Center (CDP), CT | 2,250 |
| 14 | Westbrook Center (CDP), CT | 2,220 |
| 15 | Higganum (CDP), CT | 2,089 |
| 16 | Moodus (CDP), CT | 1,982 |
| 17 | Chester Center (CDP), CT | 1,720 |
| 18 | Saybrook Manor (CDP), CT | 1,172 |
| 19 | Fenwick (borough), CT | 53 |