Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Ore Creek | Stream | | Walworth | 42 38 53 N | 088 21 13 W |
| Oregon | Populated Place | 287 | Dane | 42 55 34 N | 089 23 04 W |
| Oregon Branch | Stream | | Dane | 42 53 48 N | 089 18 48 W |
| Oregon High School | School | 285 | Dane | 42 55 57 N | 089 22 18 W |
| Oregon Post Office | Post Office | 286 | Dane | 42 55 37 N | 089 22 58 W |
| Oregon Public Library | Building | 286 | Dane | 42 55 34 N | 089 22 57 W |
| Oregon State Camp and Farm | Locale | 295 | Dane | 42 57 09 N | 089 23 48 W |
| Oregon Village Hall | Building | 287 | Dane | 42 55 34 N | 089 23 00 W |
| Orfordville | Populated Place | 271 | Rock | 42 37 39 N | 089 15 11 W |
| Orfordville Elementary School | School | 272 | Rock | 42 37 51 N | 089 15 34 W |
| Orienta Dam | Dam | 201 | Bayfield | 46 44 49 N | 091 29 05 W |
| Orienta Flowage 148 | Reservoir | 188 | Bayfield | 46 44 48 N | 091 29 07 W |
| Orienta Townhall | Building | 251 | Bayfield | 46 42 40 N | 091 26 50 W |
| Orihula | Populated Place | 229 | Winnebago | 44 12 33 N | 088 49 58 W |
| Oriole Hill School (historical) | School | 353 | Clark | 44 37 32 N | 090 31 37 W |
| Oriole Lake | Lake | 506 | Iron | 46 15 02 N | 089 55 52 W |
| Oriole Lane Elementary School | School | 207 | Ozaukee | 43 15 09 N | 087 55 54 W |
| Orion | Populated Place | 219 | Richland | 43 12 11 N | 090 25 40 W |
| Orion Mussel Bed State Natural Area | Park | 202 | Richland | 43 12 28 N | 090 21 49 W |
| Ormsby | Populated Place | 468 | Langlade | 45 15 22 N | 089 15 09 W |
| Ormsby Dam | Dam | 463 | Langlade | 45 15 25 N | 089 14 56 W |
| Ormsby Hall | Building | 236 | Outagamie | 44 15 38 N | 088 24 02 W |
| Ormsby Pond | Reservoir | 463 | Langlade | 45 15 25 N | 089 14 56 W |
| Ormsby Pond 18 | Reservoir | 464 | Langlade | 45 15 24 N | 089 15 00 W |
| Oronto Bay | Bay | 183 | Iron | 46 34 09 N | 090 26 10 W |
| Oronto Creek | Stream | | Iron | 46 33 46 N | 090 26 16 W |
| Orr Lake | Lake | 266 | Polk | 45 37 20 N | 092 40 47 W |
| Orr School | School | 293 | Polk | 45 37 19 N | 092 40 23 W |
| Orton Park | Park | 267 | Dane | 43 04 50 N | 089 21 46 W |
| Orton School (historical) | School | 378 | Marathon | 44 47 39 N | 089 32 47 W |
| Orva | Populated Place | 437 | Iron | 46 27 07 N | 090 13 54 W |
| Orville Beach Memorial Manual Training School | School | 233 | Winnebago | 44 01 12 N | 088 32 24 W |
| Osborn School (historical) | School | 300 | Fond du Lac | 43 47 49 N | 088 47 09 W |
| Oscar-Jenny Lake | Lake | 470 | Oneida | 45 37 16 N | 089 40 09 W |
| Osceola | Populated Place | 248 | Polk | 45 19 14 N | 092 42 18 W |
| Osceola Air Force Station (historical) | Military (Historical) | | Polk | 45 15 06 N | 092 38 36 W |
| Osceola Bedrock Glades State Natural Area | Park | 45 | Polk | 45 20 59 N | 092 41 09 W |
| Osceola Cemetery | Cemetery | 190 | Grant | 42 39 44 N | 090 42 16 W |
| Osceola Creek | Stream | | Polk | 45 19 15 N | 092 42 33 W |
| Osceola Lake | Lake | 272 | Polk | 45 17 38 N | 092 39 04 W |
| Osceola Lake | Lake | 513 | Vilas | 46 07 35 N | 089 19 08 W |
| Osceola Municipal Airfield | Airport | 273 | Polk | 45 18 28 N | 092 41 12 W |
| Osceola State Fish Hatchery | Locale | 257 | Polk | 45 20 46 N | 092 40 37 W |
| Osgood Lake | Lake | 381 | Sawyer | 46 04 56 N | 091 22 51 W |
| Osh-O-Nee Midway Boat Ramp | Locale | 229 | Winnebago | 44 06 19 N | 088 29 02 W |
| Oshkosh | Populated Place | 234 | Winnebago | 44 01 29 N | 088 32 33 W |
| Oshkosh Christian School | School | 237 | Winnebago | 44 03 36 N | 088 33 08 W |
| Oshkosh City Hall | Building | 234 | Winnebago | 44 01 16 N | 088 32 31 W |
| Oshkosh Congregation of Jehovahs Witnesses | Church | 238 | Winnebago | 44 01 56 N | 088 36 59 W |
| Oshkosh Country Club | Locale | 230 | Winnebago | 43 57 54 N | 088 31 23 W |
| Oshkosh Creek | Stream | | Menominee | 44 52 59 N | 088 39 16 W |
| Oshkosh Foursquare Gospel Church | Church | 234 | Winnebago | 44 01 23 N | 088 32 38 W |
| Oshkosh Grand Opera House | Building | 231 | Winnebago | 44 01 04 N | 088 32 20 W |
| Oshkosh Post Office | Post Office | 231 | Winnebago | 44 01 02 N | 088 32 03 W |
| Oshkosh Public Library | Building | 232 | Winnebago | 44 01 05 N | 088 32 09 W |
| Oshkosh Public Museum | Building | 232 | Winnebago | 44 02 02 N | 088 33 29 W |
| Oshkosh Reefs | Bar | 228 | Winnebago | 44 00 08 N | 088 30 43 W |
| Oshkosh Special Education School | School | 232 | Winnebago | 44 01 11 N | 088 34 26 W |
| Oshkosh State Normal School Historic District | Park | 235 | Winnebago | 44 01 38 N | 088 33 03 W |
| Oshkosh Waterworks | Locale | 229 | Winnebago | 44 01 06 N | 088 31 04 W |
| Oshkosh-Larsen Trail Prairies State Natural Area | Park | 44 | Winnebago | 44 08 20 N | 088 37 28 W |
| Oslo Dam | Dam | 228 | Manitowoc | 44 05 56 N | 087 49 23 W |
| Osman | Populated Place | 244 | Manitowoc | 43 58 07 N | 087 49 15 W |
| Osseo | Populated Place | 292 | Trempealeau | 44 34 20 N | 091 13 39 W |
| Osseo Area Medical Center | Hospital | 297 | Trempealeau | 44 34 40 N | 091 12 48 W |
| Osseo Club Pond | Reservoir | 299 | Trempealeau | 44 33 42 N | 091 13 49 W |
| Osseo Dam | Dam | 290 | Trempealeau | 44 34 36 N | 091 13 25 W |
| Osseo Elementary School | School | 305 | Trempealeau | 44 34 56 N | 091 12 46 W |
| Osseo Rod and Gun Club Dam | Dam | 299 | Trempealeau | 44 33 42 N | 091 13 49 W |
| Osseo-Fairchild High School | School | 299 | Trempealeau | 44 34 53 N | 091 13 04 W |
| Ostrander | Populated Place | 241 | Waupaca | 44 23 34 N | 088 50 16 W |
| Ostrander-Northport Cemetery | Cemetery | 243 | Waupaca | 44 23 29 N | 088 49 11 W |
| Oswego Lake | Lake | 503 | Vilas | 46 08 12 N | 089 36 35 W |
| Otis | Populated Place | 418 | Lincoln | 45 16 08 N | 089 41 36 W |
| Otsego | Populated Place | 289 | Columbia | 43 24 08 N | 089 09 58 W |
| Otsego Cemetery | Cemetery | 297 | Columbia | 43 23 57 N | 089 09 52 W |
| Ott Basin | Basin | 393 | Sauk | 43 26 05 N | 089 40 05 W |
| Ottawa | Populated Place | 286 | Waukesha | 42 58 34 N | 088 26 59 W |
| Ottawa Cemetery | Cemetery | 271 | Waukesha | 42 59 08 N | 088 27 49 W |
| Ottawa Lake | Lake | 264 | Waukesha | 42 56 19 N | 088 28 51 W |
| Ottawa Lake Recreation Area | Park | 269 | Waukesha | 42 56 24 N | 088 28 40 W |
| Ottawa Presbyterian Church | Church | 290 | Waukesha | 42 58 33 N | 088 27 01 W |
| Otter Creek | Gut | 271 | Waupaca | 44 20 37 N | 089 08 36 W |
| Otter Creek | Stream | | Bayfield | 46 14 45 N | 091 29 15 W |
| Otter Creek | Stream | | Chippewa | 45 06 33 N | 091 00 10 W |
| Otter Creek | Stream | | Crawford | 43 10 46 N | 090 55 17 W |
| Otter Creek | Stream | | Dunn | 45 02 59 N | 091 52 57 W |
| Otter Creek | Stream | | Eau Claire | 44 48 54 N | 091 28 11 W |
| Otter Creek | Stream | | Forest | 45 40 29 N | 088 42 48 W |
| Otter Creek | Stream | | Iowa | 43 09 32 N | 090 11 14 W |
| Otter Creek | Stream | | Iron | 46 01 11 N | 090 11 28 W |
| Otter Creek | Stream | | Jefferson | 42 51 22 N | 088 56 04 W |
| Otter Creek | Stream | | Lafayette | 42 40 20 N | 090 04 05 W |
| Otter Creek | Stream | | Marinette | 45 24 47 N | 088 20 40 W |
| Otter Creek | Stream | | Polk | 45 29 44 N | 092 28 24 W |
| Otter Creek | Stream | | Sauk | 43 14 25 N | 089 48 23 W |
| Otter Creek | Stream | | Sheboygan | 43 47 18 N | 087 55 04 W |
| Otter Creek | Stream | | Vernon | 43 34 08 N | 090 38 30 W |
| Otter Creek 12 3WR1178 Dam | Dam | 267 | Iowa | 43 01 48 N | 090 12 30 W |
| Otter Creek Cemetery | Cemetery | 289 | Dunn | 45 03 35 N | 091 50 57 W |
| Otter Creek Cemetery | Cemetery | 258 | Rock | 42 49 11 N | 088 56 14 W |
| Otter Creek Cemetery | Cemetery | 261 | Sauk | 43 21 28 N | 089 47 55 W |
| Otter Creek Church | Church | 330 | Iowa | 43 02 53 N | 090 16 50 W |
| Otter Creek Church (historical) | Church | 290 | Dunn | 45 03 37 N | 091 50 56 W |
| Otter Creek Oak Barrens State Natural Area | Park | 45 | Dunn | 45 05 11 N | 091 50 16 W |
| Otter Creek School | School | 297 | Lafayette | 42 40 34 N | 090 02 59 W |
| Otter Creek School | School | 262 | Rock | 42 49 25 N | 088 55 41 W |
| Otter Creek School (historical) | School | 345 | Chippewa | 44 59 15 N | 090 55 59 W |
| Otter Creek State Fishery Area | Park | 298 | Dunn | 45 06 14 N | 091 51 02 W |
| Otter Creek State Public Hunting Grounds | Park | 292 | Dunn | 45 06 02 N | 091 53 16 W |