Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Hardware Field (historical) | Park | 210 | Cuyahoga | 41 28 38 N | 081 37 56 W |
| Hardy Junction (historical) | Locale | 244 | Holmes | 40 30 27 N | 081 56 19 W |
| Hardy Run | Stream | | Holmes | 40 30 30 N | 081 56 38 W |
| Haren Run | Stream | | Monroe | 39 39 00 N | 081 05 23 W |
| Harewood Acres | Populated Place | 264 | Hamilton | 39 11 44 N | 084 23 07 W |
| Harger Cemetery | Cemetery | 323 | Scioto | 38 54 33 N | 082 56 34 W |
| Hargus Creek | Stream | | Pickaway | 39 36 18 N | 082 57 21 W |
| Hargus Lake | Reservoir | 233 | Pickaway | 39 37 36 N | 082 53 18 W |
| Hargus Lake Dam | Dam | 233 | Pickaway | 39 37 36 N | 082 53 18 W |
| Hargus Lake Trail | Trail | 254 | Pickaway | 39 37 52 N | 082 53 08 W |
| Harker School (historical) | School | 252 | Van Wert | 40 51 33 N | 084 47 03 W |
| Harkers Run | Stream | | Preble | 39 30 29 N | 084 43 01 W |
| Harkins Chapel | Church | 293 | Vinton | 39 13 51 N | 082 19 55 W |
| Harkins Chapel Cemetery | Cemetery | 286 | Vinton | 39 13 52 N | 082 20 01 W |
| Harkness Chapel | Church | 208 | Cuyahoga | 41 30 34 N | 081 36 28 W |
| Harkum School (historical) | School | 198 | Lucas | 41 34 30 N | 083 46 38 W |
| Harlan Butlerville School | School | 263 | Warren | 39 18 22 N | 084 05 08 W |
| Harlan Cemetery | Cemetery | 419 | Ashland | 40 44 28 N | 082 19 03 W |
| Harlan Park | Populated Place | 198 | Butler | 39 31 40 N | 084 23 15 W |
| Harlan Park First Church of God | Church | 198 | Butler | 39 31 43 N | 084 23 12 W |
| Harlans Run | Stream | | Warren | 39 27 38 N | 084 01 26 W |
| Harlem | Populated Place | 304 | Delaware | 40 09 06 N | 082 50 22 W |
| Harlem Cemetery | Cemetery | 305 | Delaware | 40 09 07 N | 082 50 10 W |
| Harlem Methodist Church (historical) | Church | 308 | Delaware | 40 09 08 N | 082 50 12 W |
| Harlem Post Office (historical) | Post Office | 302 | Delaware | 40 09 05 N | 082 50 22 W |
| Harlem Springs | Populated Place | 380 | Carroll | 40 31 15 N | 081 00 11 W |
| Harlem Springs Cemetery | Cemetery | 393 | Carroll | 40 31 19 N | 081 00 18 W |
| Harlem Springs Elementary School | School | 384 | Carroll | 40 31 16 N | 081 00 06 W |
| Harlem Springs Post Office | Post Office | 378 | Carroll | 40 31 15 N | 081 00 09 W |
| Harley | Populated Place | 265 | Fairfield | 39 51 11 N | 082 41 17 W |
| Harman Avenue School | School | 294 | Montgomery | 39 43 29 N | 084 10 39 W |
| Harman Run | Stream | | Mahoning | 40 55 36 N | 080 32 42 W |
| Harmar | Populated Place | 185 | Washington | 39 24 37 N | 081 27 41 W |
| Harmar Cemetery | Cemetery | 192 | Washington | 39 25 00 N | 081 27 49 W |
| Harmar Congregational Church | Church | 182 | Washington | 39 24 42 N | 081 27 40 W |
| Harmar Elementary School | School | 183 | Washington | 39 24 34 N | 081 27 30 W |
| Harmar Hill Chapel | Church | 258 | Washington | 39 24 55 N | 081 28 05 W |
| Harmar Hill Church of Christ | Church | 265 | Washington | 39 24 58 N | 081 28 21 W |
| Harmar Historic District | Park | 182 | Washington | 39 24 41 N | 081 27 34 W |
| Harmon | Populated Place | 310 | Stark | 40 42 34 N | 081 33 34 W |
| Harmon Brook | Stream | | Portage | 41 10 51 N | 081 12 27 W |
| Harmon Cemetery | Cemetery | 391 | Monroe | 39 50 19 N | 081 02 18 W |
| Harmon Cemetery | Cemetery | 234 | Putnam | 41 00 58 N | 083 56 39 W |
| Harmon Cemetery | Cemetery | 373 | Scioto | 38 59 55 N | 083 14 05 W |
| Harmon Creek | Stream | | Harrison | 40 16 21 N | 080 55 34 W |
| Harmon Field | Park | 298 | Crawford | 40 48 50 N | 082 58 13 W |
| Harmon Field | Park | 230 | Montgomery | 39 38 12 N | 084 16 46 W |
| Harmon Field | Park | 217 | Montgomery | 39 40 45 N | 084 15 25 W |
| Harmon Field | Park | 225 | Sandusky | 41 16 24 N | 082 50 40 W |
| Harmon Field | Park | 190 | Sandusky | 41 21 25 N | 083 07 22 W |
| Harmon Field Park | Park | 364 | Logan | 40 21 45 N | 083 46 28 W |
| Harmon Golf Course | Locale | 227 | Warren | 39 25 44 N | 084 12 04 W |
| Harmon Industrial Park | Locale | 215 | Warren | 39 26 13 N | 084 13 20 W |
| Harmon Memorial Park | Park | 372 | Champaign | 40 07 38 N | 083 57 51 W |
| Harmon Middle School | School | 340 | Portage | 41 18 55 N | 081 21 24 W |
| Harmon Park | Park | 301 | Shelby | 40 17 45 N | 084 09 31 W |
| Harmon Park | Park | 218 | Warren | 39 25 51 N | 084 11 58 W |
| Harmon Playground | Park | 268 | Auglaize | 40 34 19 N | 084 12 04 W |
| Harmon Ridge | Ridge | 410 | Monroe | 39 43 19 N | 080 55 54 W |
| Harmon Ridge | Ridge | 332 | Monroe | 39 38 15 N | 081 08 58 W |
| Harmon Run | Stream | | Monroe | 39 27 03 N | 084 19 20 W |
| Harmon-salt Creek Church | Church | 373 | Scioto | 38 59 55 N | 083 14 02 W |
| Harmons Landing | Populated Place | 267 | Auglaize | 40 30 42 N | 084 26 34 W |
| Harmont Park | Park | 344 | Stark | 40 49 32 N | 081 19 51 W |
| Harmony | Populated Place | 325 | Clark | 39 55 22 N | 083 41 50 W |
| Harmony Baptist Church | Church | 186 | Lucas | 41 40 27 N | 083 32 49 W |
| Harmony Cemetery | Cemetery | 293 | Adams | 38 46 08 N | 083 29 13 W |
| Harmony Cemetery | Cemetery | 390 | Belmont | 39 55 34 N | 081 11 57 W |
| Harmony Cemetery | Cemetery | 347 | Carroll | 40 36 30 N | 081 15 44 W |
| Harmony Cemetery | Cemetery | 383 | Coshocton | 40 25 40 N | 082 04 55 W |
| Harmony Cemetery | Cemetery | 313 | Guernsey | 39 56 21 N | 081 36 53 W |
| Harmony Cemetery | Cemetery | 318 | Perry | 39 37 59 N | 082 22 34 W |
| Harmony Chapel | Church | 357 | Morrow | 40 29 48 N | 082 44 57 W |
| Harmony Chapel Cemetery | Cemetery | 357 | Morrow | 40 29 47 N | 082 44 54 W |
| Harmony Church | Church | 304 | Fayette | 39 34 25 N | 083 28 16 W |
| Harmony Church | Church | 317 | Guernsey | 39 56 23 N | 081 36 55 W |
| Harmony Church | Church | 172 | Lawrence | 38 29 18 N | 082 28 20 W |
| Harmony Church | Church | 359 | Licking | 40 11 33 N | 082 38 29 W |
| Harmony Church | Church | 360 | Licking | 40 04 52 N | 082 40 02 W |
| Harmony Church | Church | 370 | Morrow | 40 32 41 N | 082 38 50 W |
| Harmony Church | Church | 369 | Morrow | 40 27 36 N | 082 46 01 W |
| Harmony Church | Church | 253 | Seneca | 41 01 46 N | 083 11 11 W |
| Harmony Church | Church | 227 | Van Wert | 40 55 49 N | 084 26 10 W |
| Harmony Church (historical) | Church | 387 | Coshocton | 40 25 42 N | 082 04 55 W |
| Harmony Community School | School | | Hamilton | 39 12 12 N | 084 27 46 W |
| Harmony Estates Mobile Home Park | Populated Place | 337 | Clark | 39 55 39 N | 083 40 12 W |
| Harmony Freewill Baptist Church | Church | 219 | Franklin | 39 54 33 N | 082 59 09 W |
| Harmony Grove School (historical) | School | 246 | Warren | 39 32 47 N | 084 00 17 W |
| Harmony Hill School (historical) | School | 306 | Morgan | 39 40 32 N | 081 49 53 W |
| Harmony Hollow | Valley | | Muskingum | 39 51 33 N | 081 50 24 W |
| Harmony Homestead Airport | Airport | 287 | Medina | 41 04 58 N | 082 02 36 W |
| Harmony Lake | Reservoir | 308 | Wayne | 40 47 36 N | 081 44 05 W |
| Harmony Lake Dam | Dam | 308 | Wayne | 40 47 36 N | 081 44 05 W |
| Harmony Post Office (historical) | Post Office | 332 | Clark | 39 55 20 N | 083 41 50 W |
| Harmony School (historical) | School | 250 | Adams | 38 56 38 N | 083 30 54 W |
| Harmony School (historical) | School | 300 | Guernsey | 39 51 07 N | 081 37 31 W |
| Harmony School (historical) | School | 254 | Guernsey | 39 56 51 N | 081 37 10 W |
| Harmony School (historical) | School | 326 | Hardin | 40 34 05 N | 083 45 15 W |
| Harmony School (historical) | School | 207 | Jefferson | 40 18 07 N | 080 37 06 W |
| Harmony School (historical) | School | 257 | Muskingum | 39 51 48 N | 081 49 40 W |
| Harmony United Brethren Church (historical) | Church | 321 | Perry | 39 38 00 N | 082 22 33 W |
| Harmony United Methodist Church | Church | 215 | Jefferson | 40 18 31 N | 080 37 01 W |
| Harold School (historical) | School | 329 | Fayette | 39 41 22 N | 083 33 07 W |
| Harold T Clark Library | Building | 204 | Cuyahoga | 41 30 42 N | 081 36 48 W |
| Harper | Populated Place | 399 | Logan | 40 25 44 N | 083 42 30 W |
| Harper | Populated Place | 282 | Ross | 39 21 53 N | 083 15 42 W |
| Harper Cemetery | Cemetery | 415 | Logan | 40 25 07 N | 083 42 08 W |
| Harper Cemetery | Cemetery | 285 | Ross | 39 21 57 N | 083 15 41 W |
| Harper Ditch | Canal | 334 | Portage | 41 14 31 N | 081 15 36 W |
| Harper Hollow | Valley | | Jackson | 39 05 15 N | 082 44 34 W |