Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Cosmos | Populated Place | 313 | Darke | 40 16 02 N | 084 46 46 W |
| Cosmos Post Office (historical) | Post Office | 314 | Darke | 40 16 00 N | 084 46 45 W |
| Cosmos School (historical) | School | 314 | Darke | 40 16 01 N | 084 46 42 W |
| Cossett Creek | Stream | | Medina | 41 13 38 N | 081 55 22 W |
| Cost Cemetery | Cemetery | 329 | Logan | 40 17 08 N | 083 58 22 W |
| Costonia | Populated Place | 220 | Jefferson | 40 25 37 N | 080 37 04 W |
| Costonia Post Office (historical) | Post Office | 219 | Jefferson | 40 25 35 N | 080 37 04 W |
| Cotillion Village | Populated Place | 256 | Hamilton | 39 06 25 N | 084 38 25 W |
| Cotner Ditch | Canal | 271 | Allen | 40 48 43 N | 083 56 50 W |
| Cottage Chapel (historical) | Church | 202 | Cuyahoga | 41 30 10 N | 081 39 07 W |
| Cottage Grove | Populated Place | 321 | Summit | 40 59 19 N | 081 30 43 W |
| Cottage Grove Elementary School | School | 325 | Summit | 40 59 37 N | 081 30 31 W |
| Cottage Grove Lake | Reservoir | 302 | Summit | 40 59 15 N | 081 31 18 W |
| Cottage Hill | Populated Place | 278 | Muskingum | 40 00 58 N | 082 11 18 W |
| Cottage Hill School (historical) | School | 348 | Knox | 40 32 35 N | 082 20 07 W |
| Cottagehill Post Office (historical) | Post Office | 268 | Muskingum | 40 01 00 N | 082 11 20 W |
| Cotterman Hall | Building | 238 | Franklin | 39 57 15 N | 082 56 13 W |
| Cotton Bridge | Bridge | 214 | Morgan | 39 41 24 N | 081 48 14 W |
| Cotton Eye Hollow | Valley | | Scioto | 38 44 03 N | 083 12 51 W |
| Cotton Hill | Summit | 319 | Morgan | 39 38 24 N | 081 49 23 W |
| Cotton Private Cemetery | Cemetery | 341 | Mahoning | 41 05 56 N | 080 45 20 W |
| Cotton Run | Stream | | Butler | 39 27 26 N | 084 32 13 W |
| Cotton Run Cemetery | Cemetery | 239 | Butler | 39 29 10 N | 084 30 54 W |
| Cotton Run School (historical) | School | 227 | Butler | 39 30 02 N | 084 32 01 W |
| Cotton Slash (historical) | Locale | 306 | Union | 40 21 02 N | 083 21 60 W |
| Cottonwood Bar | Bar | 157 | Gallia | 38 35 50 N | 082 14 44 W |
| Cottonwood Ditch | Canal | 293 | Hardin | 40 41 21 N | 083 48 08 W |
| Cottonwood Elementary School | School | 248 | Hamilton | 39 13 19 N | 084 31 19 W |
| Cottonwood Landing | Locale | 159 | Gallia | 38 35 57 N | 082 15 17 W |
| Cottonwood Park | Park | 295 | Montgomery | 39 50 15 N | 084 06 38 W |
| Cottonwood Picnic Area | Locale | 195 | Cuyahoga | 41 25 57 N | 081 50 59 W |
| Cottonwood Swale | Stream | | Ottawa | 41 28 50 N | 083 06 40 W |
| Cottrell Cemetery | Cemetery | 207 | Gallia | 38 43 31 N | 082 13 19 W |
| Cottrill School (historical) | School | 216 | Vinton | 39 11 42 N | 082 19 49 W |
| Couchman School (historical) | School | 326 | Champaign | 40 13 44 N | 083 45 10 W |
| Coulby Park | Park | 235 | Lake | 41 35 45 N | 081 28 38 W |
| Coulter | Populated Place | 310 | Richland | 40 41 33 N | 082 20 39 W |
| Coulter Avenue Park | Park | 200 | Cuyahoga | 41 34 28 N | 081 31 30 W |
| Coulter Cemetery | Cemetery | 327 | Clinton | 39 30 33 N | 083 41 06 W |
| Coulter Cemetery | Cemetery | 315 | Crawford | 40 43 59 N | 082 55 27 W |
| Coulter Private Cemetery | Cemetery | 365 | Jefferson | 40 24 01 N | 080 42 05 W |
| Coulters Run | Stream | | Butler | 39 29 20 N | 084 40 30 W |
| Country Acres Golf Course | Locale | 221 | Putnam | 41 01 46 N | 084 11 36 W |
| Country Care Center | Building | 189 | Sandusky | 41 21 36 N | 083 05 13 W |
| Country Charm Shopping Center | Locale | 193 | Wood | 41 32 39 N | 083 37 13 W |
| Country Club Acres | Populated Place | 260 | Hamilton | 39 10 52 N | 084 22 46 W |
| Country Club Cemetery | Cemetery | 177 | Scioto | 38 48 24 N | 083 00 43 W |
| Country Fair Shopping Center | Locale | 235 | Muskingum | 39 58 53 N | 082 01 12 W |
| Country Haven Mobile Home Park | Populated Place | 263 | Clark | 39 53 37 N | 084 00 50 W |
| Country Manor Estates | Populated Place | 203 | Wood | 41 25 44 N | 083 40 35 W |
| Country Meadows | Populated Place | 190 | Wood | 41 33 38 N | 083 30 31 W |
| Country Square Shopping Center | Locale | 292 | Montgomery | 39 52 35 N | 084 18 33 W |
| Countryman Cemetery | Cemetery | 262 | Highland | 39 05 36 N | 083 27 41 W |
| Countrymans Creek | Stream | | Cuyahoga | 41 26 45 N | 081 45 15 W |
| Countryside Park | Park | 187 | Sandusky | 41 21 38 N | 083 05 05 W |
| Countryside Plaza Shopping Center | Locale | 277 | Warren | 39 24 20 N | 084 12 36 W |
| Counts Cemetery | Cemetery | 322 | Madison | 39 42 57 N | 083 28 05 W |
| Counts Run | Stream | | Shelby | 40 20 04 N | 084 04 55 W |
| County Cemetery | Cemetery | 340 | Knox | 40 20 49 N | 082 33 14 W |
| County Childrens Home | Building | 210 | Ashtabula | 41 52 25 N | 080 46 06 W |
| County Fair Shopping Center | Locale | 335 | Stark | 40 47 50 N | 081 25 29 W |
| County Home Cemetery | Cemetery | 349 | Ashland | 40 48 21 N | 082 15 58 W |
| County Home Cemetery | Cemetery | 370 | Carroll | 40 37 03 N | 081 04 02 W |
| County Home Cemetery | Cemetery | 319 | Crawford | 40 46 23 N | 082 55 12 W |
| County Home Cemetery | Cemetery | 322 | Darke | 40 03 59 N | 084 37 07 W |
| County Home Cemetery | Cemetery | 387 | Geauga | 41 30 30 N | 081 10 58 W |
| County Home Cemetery | Cemetery | 287 | Highland | 39 10 59 N | 083 32 42 W |
| County Home Cemetery | Cemetery | 332 | Logan | 40 24 01 N | 083 48 32 W |
| County Home Cemetery | Cemetery | 360 | Monroe | 39 46 50 N | 081 06 52 W |
| County Home Cemetery | Cemetery | 362 | Morrow | 40 33 55 N | 082 48 28 W |
| County Home Cemetery | Cemetery | 219 | Paulding | 41 09 01 N | 084 33 15 W |
| County Home Cemetery | Cemetery | 323 | Preble | 39 45 43 N | 084 38 53 W |
| County Home Cemetery | Cemetery | 187 | Sandusky | 41 21 38 N | 083 04 54 W |
| County Home Cemetery | Cemetery | 241 | Seneca | 41 04 39 N | 083 09 49 W |
| County Home Cemetery | Cemetery | 307 | Shelby | 40 15 04 N | 084 11 54 W |
| County Infirmary Cemetery | Cemetery | 285 | Fairfield | 39 44 20 N | 082 35 21 W |
| County Infirmary Cemetery | Cemetery | 282 | Montgomery | 39 44 18 N | 084 16 58 W |
| County Infirmary Farm | Hospital | 275 | Trumbull | 41 16 44 N | 080 50 10 W |
| County Line | Populated Place | 285 | Preble | 39 44 41 N | 084 28 55 W |
| County Line (historical) | Populated Place | 273 | Miami | 39 55 15 N | 084 18 53 W |
| County Line Cemetery | Cemetery | 409 | Ashland | 40 43 05 N | 082 13 20 W |
| County Line Church | Church | 291 | Allen | 40 48 05 N | 083 52 50 W |
| County Line Mennonite Cemetery | Cemetery | 366 | Wayne | 40 49 18 N | 081 38 54 W |
| County Line Mennonite Church | Church | 365 | Wayne | 40 49 21 N | 081 38 55 W |
| County Line School (historical) | School | 318 | Perry | 39 53 42 N | 082 27 57 W |
| County Line Siding (historical) | Locale | 211 | Scioto | 38 56 43 N | 082 53 34 W |
| County Nursing Home Number Two for the Aged | Building | 210 | Cuyahoga | 41 29 09 N | 081 42 43 W |
| County Pre-Release Center and Ohio Correctional Medical Center | Hospital | 215 | Franklin | 39 55 04 N | 083 00 58 W |
| Court Street Elementary School | School | 209 | Pickaway | 39 35 16 N | 082 57 07 W |
| Courthouse Square | Building | 196 | Cuyahoga | 41 30 08 N | 081 41 55 W |
| Courtright (historical) | Populated Place | 222 | Ross | 39 26 54 N | 082 55 39 W |
| Courtright Memorial Library | Building | 259 | Franklin | 40 07 35 N | 082 56 13 W |
| Courtright School | School | 234 | Franklin | 39 56 14 N | 082 53 49 W |
| Cousins Cemetery | Cemetery | 317 | Pike | 39 10 49 N | 083 06 21 W |
| Couts Family Cemetery | Cemetery | 336 | Tuscarawas | 40 13 57 N | 081 28 13 W |
| Cove | Locale | 208 | Jackson | 39 00 51 N | 082 44 51 W |
| Cove Cottage Area | Populated Place | 294 | Carroll | 40 32 47 N | 081 14 55 W |
| Cove Park | Park | 201 | Cuyahoga | 41 29 15 N | 081 46 39 W |
| Cove Run | Stream | | Ross | 39 14 11 N | 083 17 14 W |
| Cove School (historical) | School | 227 | Jackson | 39 00 55 N | 082 43 20 W |
| Cove Springs United Church of Christ | Church | 290 | Miami | 39 59 59 N | 084 06 10 W |
| Covedale | Populated Place | 270 | Hamilton | 39 07 16 N | 084 36 23 W |
| Covedale Cemetery | Cemetery | 267 | Hamilton | 39 07 43 N | 084 37 04 W |
| Covedale Elementary School | School | 280 | Hamilton | 39 07 27 N | 084 36 26 W |
| Covedale Post Office (historical) | Post Office | 270 | Hamilton | 39 07 15 N | 084 36 25 W |
| Covenant Baptist Church | Church | 232 | Lake | 41 35 52 N | 081 28 28 W |
| Covenant Baptist Church | Church | 332 | Summit | 40 59 30 N | 081 38 42 W |
| Covenant Lutheran Church | Church | 369 | Champaign | 40 07 42 N | 083 57 39 W |
| Covenant Presbyterian Church | Church | 289 | Clark | 39 55 38 N | 083 48 32 W |
| Covenant Presbyterian Church | Church | 213 | Columbiana | 40 35 49 N | 080 39 43 W |