| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| O'Bryonsville | city | Ohio | United States | 39.13 | -84.46 | 830 | |
| O'Connor Point | city | Ohio | United States | 40.50 | -83.85 | 997 | |
| Oak | city | Ohio | United States | 39.74 | -80.94 | 1197 | |
| Oak Avenue Mobile Home Park | city | Ohio | United States | 41.05 | -83.64 | 830 | |
| Oak Grove | city | Ohio | United States | 39.45 | -81.47 | 830 | |
| Oak Grove | city | Ohio | United States | 39.89 | -83.08 | 830 | |
| Oak Harbor | city | Ohio | United States | 41.51 | -83.15 | 830 | |
| Oak Hill | city | Ohio | United States | 40.41 | -82.24 | 997 | |
| Oak Hill | city | Ohio | United States | 38.89 | -82.57 | 830 | |
| Oak Hill Mobile Home Park | city | Ohio | United States | 41.22 | -80.78 | 997 | |
| Oak Hill Mobile Home Village | city | Ohio | United States | 40.04 | -81.46 | 1000 | |
| Oak Hill Village | city | Ohio | United States | 41.66 | -81.40 | 830 | |
| Oak Knoll | city | Ohio | United States | 40.56 | -83.15 | 997 | |
| Oak Leaf Mobile Home Park | city | Ohio | United States | 41.18 | -81.51 | 1023 | |
| Oak Manor | city | Ohio | United States | 40.80 | -81.47 | 1095 | |
| Oak Meadows | city | Ohio | United States | 41.46 | -84.60 | 830 | |
| Oak Meadows | city | Ohio | United States | 41.54 | -83.60 | 830 | |
| Oak Mobile Home Court | city | Ohio | United States | 41.45 | -84.00 | 830 | |
| Oak Park | city | Ohio | United States | 40.25 | -81.00 | 1099 | |
| Oak Park | city | Ohio | United States | 39.61 | -82.89 | 830 | |
| Oak Park Mobile Home Park | city | Ohio | United States | 40.98 | -81.66 | 1095 | |
| Oak Ridge | city | Ohio | United States | 40.84 | -81.50 | 1095 | |
| Oak Ridge | city | Ohio | United States | 39.66 | -84.14 | 997 | |
| Oak Run | city | Ohio | United States | 40.01 | -83.14 | 898 | |
| Oakcrest | city | Ohio | United States | 39.95 | -83.77 | 1000 | |
| Oakdale | city | Ohio | United States | 39.21 | -84.61 | 898 | |
| Oakdale | city | Ohio | United States | 39.69 | -84.13 | 997 | |
| Oakdale | city | Ohio | United States | 39.52 | -82.09 | 830 | |
| Oakdale | city | Ohio | United States | 40.33 | -83.08 | 898 | |
| Oakdale (historical) | city | Ohio | United States | 41.13 | -83.96 | 830 | |
| Oakfield | city | Ohio | United States | 41.41 | -80.85 | 921 | |
| Oakfield | city | Ohio | United States | 39.66 | -82.12 | 898 | |
| Oakgrove | city | Ohio | United States | 39.85 | -83.89 | 980 | |
| Oakgrove | city | Ohio | United States | 40.14 | -81.23 | 1197 | |
| Oakgrove (historical) | city | Ohio | United States | 38.99 | -81.91 | 830 | |
| Oakland | city | Ohio | United States | 39.74 | -84.14 | 898 | |
| Oakland | city | Ohio | United States | 40.05 | -82.78 | 1066 | |
| Oakland | city | Ohio | United States | 39.46 | -84.35 | 830 | |
| Oakland | city | Ohio | United States | 39.08 | -82.71 | 830 | |
| Oakland | city | Ohio | United States | 39.51 | -84.40 | 830 | |
| Oakland | city | Ohio | United States | 39.60 | -82.76 | 1023 | |
| Oakland | city | Ohio | United States | 39.48 | -83.91 | 997 | |
| Oakland (historical) | city | Ohio | United States | 39.94 | -81.98 | 830 | |
| Oakland Mobile Home Park | city | Ohio | United States | 40.57 | -83.15 | 944 | |
| Oakley | city | Ohio | United States | 39.15 | -84.42 | 830 | |
| Oakley Square | city | Ohio | United States | 39.15 | -84.43 | 830 | |
| Oakmont | city | Ohio | United States | 41.54 | -83.60 | 830 | |
| Oakmont Creek | city | Ohio | United States | 40.03 | -84.22 | 869 | |
| Oakmont Village | city | Ohio | United States | 39.93 | -83.15 | 898 | |
| Oakpoint (historical) | city | Ohio | United States | 41.44 | -82.25 | 830 | |
| Oakshade | city | Ohio | United States | 41.67 | -84.15 | 830 | |
| Oakthorpe | city | Ohio | United States | 39.81 | -82.44 | 912 | |
| Oakview | city | Ohio | United States | 40.69 | -84.21 | 846 | |
| Oakwood | city | Ohio | United States | 39.73 | -84.17 | 997 | |
| Oakwood | city | Ohio | United States | 39.98 | -81.56 | 830 | |
| Oakwood | city | Ohio | United States | 41.37 | -81.51 | 1043 | |
| Oakwood | city | Ohio | United States | 41.10 | -84.38 | 830 | |
| Oakwood Acres | city | Ohio | United States | 39.94 | -83.29 | 898 | |
| Oakwood Mobile Home Park | city | Ohio | United States | 41.88 | -80.78 | 830 | |
| Oakwood Park | city | Ohio | United States | 39.43 | -81.45 | 830 | |
| Oakwood Village | city | Ohio | United States | 39.97 | -83.78 | 997 | |
| Oakwood Village | city | Ohio | United States | 39.59 | -84.25 | 941 | |
| Obad (historical) | city | Ohio | United States | 38.96 | -82.37 | 830 | |
| Oberlin | city | Ohio | United States | 41.29 | -82.22 | 830 | |
| Oberlin Beach | city | Ohio | United States | 41.38 | -82.51 | 830 | |
| Obetz | city | Ohio | United States | 39.88 | -82.95 | 830 | |
| Oceola | city | Ohio | United States | 40.84 | -83.09 | 898 | |
| Oco | city | Ohio | United States | 40.11 | -81.00 | 1122 | |
| Oconorville (historical) | city | Ohio | United States | 39.66 | -82.16 | 898 | |
| Octa | city | Ohio | United States | 39.60 | -83.61 | 997 | |
| Odbert (historical) | city | Ohio | United States | 40.48 | -81.49 | 997 | |
| Odell | city | Ohio | United States | 40.15 | -81.48 | 898 | |
| Offenbacher Mobile Home Park | city | Ohio | United States | 40.74 | -84.08 | 895 | |
| Ogden | city | Ohio | United States | 39.43 | -83.91 | 987 | |
| Ogles (historical) | city | Ohio | United States | 39.54 | -83.83 | 997 | |
| Ogleton (historical) | city | Ohio | United States | 39.47 | -84.74 | 898 | |
| Ogontz | city | Ohio | United States | 41.34 | -82.46 | 830 | |
| Ohio City | city | Ohio | United States | 40.77 | -84.62 | 830 | |
| Ohio City | city | Ohio | United States | 41.48 | -81.71 | 830 | |
| Ohio Furnace | city | Ohio | United States | 38.60 | -82.78 | 830 | |
| Ohio Shores | city | Ohio | United States | 41.47 | -81.89 | 830 | |
| Ohlton (historical) | city | Ohio | United States | 41.12 | -80.78 | 1026 | |
| Ohltown | city | Ohio | United States | 41.13 | -80.79 | 1026 | |
| Ohmer Park | city | Ohio | United States | 39.74 | -84.15 | 928 | |
| Oil Center (historical) | city | Ohio | United States | 41.21 | -83.64 | 830 | |
| Oil Station | city | Ohio | United States | 41.26 | -83.01 | 830 | |
| Okeana | city | Ohio | United States | 39.35 | -84.77 | 830 | |
| Okey | city | Ohio | United States | 38.63 | -82.37 | 898 | |
| Oklahoma (historical) | city | Ohio | United States | 39.79 | -84.63 | 1000 | |
| Okolona | city | Ohio | United States | 41.36 | -84.22 | 830 | |
| Olbers | city | Ohio | United States | 39.48 | -82.11 | 879 | |
| Old Chinatown | city | Ohio | United States | 41.51 | -81.68 | 830 | |
| Old Fort | city | Ohio | United States | 41.24 | -83.15 | 830 | |
| Old Gore | city | Ohio | United States | 39.58 | -82.30 | 830 | |
| Old Pimtown (historical) | city | Ohio | United States | 40.24 | -83.76 | 1079 | |
| Old Town | city | Ohio | United States | 40.44 | -81.46 | 898 | |
| Old Washington | city | Ohio | United States | 40.04 | -81.44 | 1007 | |
| Olde Falls Village | city | Ohio | United States | 39.99 | -82.04 | 830 | |
| Olde Town Mobile Home Park | city | Ohio | United States | 41.11 | -83.80 | 830 | |
| Olde West Chester | city | Ohio | United States | 39.33 | -84.41 | 830 | |
| Oldfield Estates | city | Ohio | United States | 40.22 | -83.01 | 958 | |
| Oldham | city | Ohio | United States | 40.07 | -81.60 | 830 | |
| Oldtown | city | Ohio | United States | 39.73 | -83.94 | 885 | |
| Oldtown Flats | city | Ohio | United States | 39.00 | -81.84 | 830 | |
| Olena | city | Ohio | United States | 41.15 | -82.54 | 941 | |
| Olentangy | city | Ohio | United States | 40.06 | -83.05 | 830 | |
| Olentangy | city | Ohio | United States | 40.76 | -82.87 | 1043 | |
| Olentangy Crossings | city | Ohio | United States | 40.20 | -83.03 | 898 | |
| Olentangy Estates | city | Ohio | United States | 40.73 | -82.80 | 1141 | |
| Olentangy Falls | city | Ohio | United States | 40.21 | -83.05 | 885 | |
| Olentangy Glade | city | Ohio | United States | 40.14 | -83.00 | 928 | |
| Olentangy High Bluffs | city | Ohio | United States | 40.13 | -83.02 | 898 | |
| Olentangy Meadows | city | Ohio | United States | 40.14 | -83.01 | 931 | |
| Olive Branch | city | Ohio | United States | 39.08 | -84.23 | 830 | |
| Olive Furnace | city | Ohio | United States | 38.76 | -82.63 | 846 | |
| Olive Green | city | Ohio | United States | 39.74 | -81.61 | 1000 | |
| Olive Green | city | Ohio | United States | 40.32 | -82.83 | 1089 | |
| Olivesburg | city | Ohio | United States | 40.89 | -82.43 | 1115 | |
| Olivett | city | Ohio | United States | 40.02 | -81.14 | 1197 | |
| Ollins Corners | city | Ohio | United States | 41.80 | -80.67 | 908 | |
| Olmsted | city | Ohio | United States | 41.41 | -81.90 | 830 | |
| Olmsted Falls | city | Ohio | United States | 41.38 | -81.91 | 830 | |
| Olmsted Trailer Park | city | Ohio | United States | 41.37 | -81.92 | 830 | |
| Olszeski Town | city | Ohio | United States | 40.19 | -80.79 | 898 | |
| Olwine Mobile Home Park | city | Ohio | United States | 40.09 | -84.61 | 1033 | |
| Olympia (historical) | city | Ohio | United States | 39.54 | -83.38 | 912 | |
| Olympic Hills | city | Ohio | United States | 39.95 | -83.79 | 997 | |
| Omar | city | Ohio | United States | 41.12 | -82.87 | 898 | |
| Omega | city | Ohio | United States | 39.15 | -82.91 | 830 | |
| Oneida | city | Ohio | United States | 39.48 | -84.39 | 830 | |
| Oneida | city | Ohio | United States | 40.70 | -81.15 | 1092 | |
| Ontario | city | Ohio | United States | 40.76 | -82.59 | 1669 | |
| Opera (historical) | city | Ohio | United States | 39.91 | -82.16 | 997 | |
| Opperman | city | Ohio | United States | 39.89 | -81.60 | 997 | |
| Oran | city | Ohio | United States | 40.29 | -84.32 | 974 | |
| Orange | city | Ohio | United States | 40.17 | -83.01 | 931 | |
| Orange | city | Ohio | United States | 40.29 | -81.68 | 849 | |
| Orange | city | Ohio | United States | 41.45 | -81.48 | 1181 | |
| Orange Center | city | Ohio | United States | 41.46 | -81.44 | 1030 | |
| Orangeburg (historical) | city | Ohio | United States | 39.84 | -84.75 | 1190 | |
| Orangeville | city | Ohio | United States | 41.34 | -80.52 | 928 | |
| Orbiston | city | Ohio | United States | 39.49 | -82.17 | 830 | |
| Orchard Acres | city | Ohio | United States | 40.86 | -81.42 | 1095 | |
| Orchard Acres | city | Ohio | United States | 39.32 | -84.36 | 898 | |
| Orchard Beach | city | Ohio | United States | 41.41 | -82.41 | 830 | |
| Orchard Grove | city | Ohio | United States | 41.71 | -81.26 | 830 | |
| Orchard Heights | city | Ohio | United States | 40.77 | -81.35 | 1099 | |
| Orchard Hill | city | Ohio | United States | 38.81 | -82.21 | 830 | |
| Orchard Island | city | Ohio | United States | 40.48 | -83.89 | 987 | |
| Orchard Lane Trailer Court | city | Ohio | United States | 41.10 | -83.98 | 830 | |
| Orchard Mobile Home Park | city | Ohio | United States | 41.63 | -81.42 | 830 | |
| Orchard View | city | Ohio | United States | 41.60 | -83.42 | 830 | |
| Oregon | city | Ohio | United States | 41.64 | -83.49 | 830 | |
| Oregon Corners | city | Ohio | United States | 41.17 | -81.40 | 1049 | |
| Oregonia | city | Ohio | United States | 39.45 | -84.10 | 830 | |
| Oreton | city | Ohio | United States | 39.16 | -82.41 | 830 | |
| Oreville | city | Ohio | United States | 39.58 | -82.27 | 875 | |
| Orient | city | Ohio | United States | 39.80 | -83.15 | 830 | |
| Orland | city | Ohio | United States | 39.38 | -82.42 | 872 | |
| Orpheus | city | Ohio | United States | 38.96 | -82.46 | 830 | |
| Orrville | city | Ohio | United States | 40.84 | -81.76 | 1066 | |
| Orrville Trailer Park | city | Ohio | United States | 40.84 | -81.77 | 1092 | |
| Orwell | city | Ohio | United States | 41.54 | -80.87 | 902 | |
| Osage | city | Ohio | United States | 40.47 | -80.72 | 1102 | |
| Osborn Corners | city | Ohio | United States | 41.20 | -81.68 | 1013 | |
| Osceola | city | Ohio | United States | 39.34 | -84.06 | 830 | |
| Osgood | city | Ohio | United States | 40.34 | -84.50 | 948 | |
| Osterholt Mobile Home Park | city | Ohio | United States | 40.42 | -84.63 | 948 | |
| Ostrander | city | Ohio | United States | 40.27 | -83.21 | 898 | |
| Otho (historical) | city | Ohio | United States | 39.68 | -81.70 | 830 | |
| Otsego | city | Ohio | United States | 40.12 | -81.76 | 830 | |
| Otsego | city | Ohio | United States | 41.45 | -83.78 | 830 | |
| Ottawa | city | Ohio | United States | 41.02 | -84.05 | 830 | |
| Ottawa Hills | city | Ohio | United States | 41.66 | -83.64 | 830 | |
| Otter | city | Ohio | United States | 40.28 | -83.42 | 997 | |
| Otterbein | city | Ohio | United States | 40.58 | -83.51 | 997 | |
| Otterbein | city | Ohio | United States | 39.95 | -84.67 | 1099 | |
| Otterbein | city | Ohio | United States | 39.45 | -84.28 | 898 | |
| Ottokee | city | Ohio | United States | 41.60 | -84.13 | 830 | |
| Ottokee Station | city | Ohio | United States | 41.60 | -84.15 | 830 | |
| Ottoville | city | Ohio | United States | 40.93 | -84.34 | 830 | |
| Otway | city | Ohio | United States | 38.87 | -83.19 | 830 | |
| Outville | city | Ohio | United States | 40.00 | -82.60 | 1013 | |
| Oval City | city | Ohio | United States | 40.90 | -81.33 | 1105 | |
| Over-The-Rhine | city | Ohio | United States | 39.11 | -84.52 | 830 | |
| Overlook Hills | city | Ohio | United States | 40.38 | -80.69 | 1013 | |
| Overlook Trailer Park | city | Ohio | United States | 40.13 | -84.36 | 921 | |
| Overpeck | city | Ohio | United States | 39.45 | -84.51 | 830 | |
| Overton | city | Ohio | United States | 40.86 | -82.01 | 918 | |
| Ovid | city | Ohio | United States | 40.04 | -82.81 | 997 | |
| Owens | city | Ohio | United States | 40.52 | -83.16 | 925 | |
| Owensville | city | Ohio | United States | 38.85 | -83.04 | 830 | |
| Owensville | city | Ohio | United States | 39.12 | -84.14 | 895 | |
| Owl Town (historical) | city | Ohio | United States | 40.01 | -83.82 | 980 | |
| Owls Town (historical) | city | Ohio | United States | 40.36 | -82.16 | 1010 | |
| Oxford | city | Ohio | United States | 39.51 | -84.75 | 898 | |
| Oxtoby (historical) | city | Ohio | United States | 39.90 | -83.70 | 1099 | |
| Ozark | city | Ohio | United States | 39.83 | -81.08 | 1197 |