Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Osborne Hill | Summit | 113 | Chester | 39 55 24 N | 075 36 25 W |
| Osburn | Populated Place | 312 | Westmoreland | 40 17 48 N | 079 21 47 W |
| Oscar | Populated Place | 331 | Armstrong | 40 50 25 N | 079 22 16 W |
| Osceola | Populated Place | 353 | Tioga | 41 58 55 N | 077 20 33 W |
| Osceola Mills | Populated Place | 457 | Clearfield | 40 51 00 N | 078 16 14 W |
| Osceola Mills Junior High School | School | 468 | Clearfield | 40 51 06 N | 078 16 23 W |
| Osceola Reservoir | Reservoir | 510 | Centre | 40 48 12 N | 078 16 03 W |
| Osceola School | School | 175 | Lancaster | 39 49 44 N | 076 14 19 W |
| Osgood | Populated Place | 302 | Mercer | 41 26 41 N | 080 22 03 W |
| Osgood Hollow | Valley | | Potter | 41 43 04 N | 077 41 02 W |
| Osgood Hollow | Valley | | Tioga | 41 50 22 N | 077 26 43 W |
| Oshaniter PO (historical) | Building | 464 | Clearfield | 40 56 15 N | 078 29 26 W |
| Oshanter | Populated Place | 385 | Clearfield | 40 56 07 N | 078 27 41 W |
| Ospeck Hollow | Valley | | Elk | 41 35 25 N | 078 31 28 W |
| Ostend | Populated Place | 397 | Clearfield | 40 52 09 N | 078 43 08 W |
| Oster Run | Stream | | Bedford | 39 45 19 N | 078 41 35 W |
| Osterburg | Populated Place | 351 | Bedford | 40 10 10 N | 078 31 13 W |
| Osterhout | Populated Place | 192 | Wyoming | 41 30 35 N | 075 53 55 W |
| Osterhout Mountain | Summit | 589 | Wyoming | 41 32 12 N | 075 53 55 W |
| Ostrander Hollow | Valley | | McKean | 41 50 17 N | 078 19 09 W |
| Oswald School (historical) | School | 491 | Clearfield | 41 01 45 N | 078 44 24 W |
| Oswayo | Populated Place | 518 | Potter | 41 55 16 N | 078 01 06 W |
| Oswayo Valley Elementary School | School | 456 | Potter | 41 57 44 N | 078 11 10 W |
| Oswayo Valley High School | School | 452 | Potter | 41 57 33 N | 078 11 27 W |
| Otelia Church | Church | 184 | Huntingdon | 40 22 01 N | 077 50 44 W |
| Otelia Mennonite Church Cemetery | Cemetery | 190 | Huntingdon | 40 21 59 N | 077 50 44 W |
| Oteyokwa Lake | Lake | 470 | Susquehanna | 41 53 49 N | 075 46 18 W |
| Oteyokwa Lake Dam | Dam | 476 | Susquehanna | 41 53 54 N | 075 45 59 W |
| Ott Cemetery | Cemetery | 533 | Elk | 41 27 40 N | 078 45 49 W |
| Ott Fork | Stream | | Lycoming | 41 19 04 N | 077 24 57 W |
| Ott Fork | Stream | | Lycoming | 41 25 47 N | 077 22 35 W |
| Ott Hill | Summit | 251 | Northampton | 40 50 58 N | 075 07 23 W |
| Ott Run | Stream | | Warren | 41 49 39 N | 079 07 39 W |
| Ott School | School | 526 | Elk | 41 27 39 N | 078 45 36 W |
| Ott Town | Populated Place | 348 | Bedford | 39 58 41 N | 078 26 47 W |
| Ottawa | Populated Place | 166 | Montour | 41 04 54 N | 076 42 13 W |
| Otter Branch | Stream | | Warren | 41 42 44 N | 079 10 02 W |
| Otter Creek | Stream | -3 | Bucks | 40 05 30 N | 074 51 30 W |
| Otter Creek | Stream | | Forest | 41 36 11 N | 079 22 35 W |
| Otter Creek | Stream | | Mercer | 41 13 26 N | 080 13 34 W |
| Otter Creek | Stream | | York | 39 52 47 N | 076 22 53 W |
| Otter Gap | Gap | 428 | Mifflin | 40 42 14 N | 077 41 16 W |
| Otter Gap Trail | Trail | 428 | Mifflin | 40 42 14 N | 077 41 16 W |
| Otter Lake | Reservoir | 349 | Monroe | 41 08 27 N | 075 09 14 W |
| Otter Run | Stream | | Elk | 41 26 49 N | 078 50 23 W |
| Otter Run | Stream | | Lycoming | 41 24 22 N | 077 20 00 W |
| Otterbein | Populated Place | 194 | Franklin | 40 07 13 N | 077 36 04 W |
| Otterbein Church | Church | 475 | Clearfield | 40 53 48 N | 078 45 21 W |
| Otterbein Church | Church | 29 | Montgomery | 40 08 03 N | 075 30 14 W |
| Otto | Populated Place | 241 | Allegheny | 40 20 12 N | 079 53 17 W |
| Otto | Populated Place | 143 | Northumberland | 40 43 08 N | 076 47 52 W |
| Otto Run | Stream | | Cambria | 40 19 51 N | 078 44 47 W |
| Otto Run | Stream | | Venango | 41 35 34 N | 079 31 28 W |
| Otto-Eldred High School | School | 468 | McKean | 41 56 15 N | 078 28 27 W |
| Ottsville | Populated Place | 121 | Bucks | 40 28 23 N | 075 09 40 W |
| Ottsville Post Office | Post Office | 152 | Bucks | 40 28 36 N | 075 09 54 W |
| Ottsville Volunteer Fire Company- Station 49 | Building | 123 | Bucks | 40 28 21 N | 075 09 37 W |
| Oughoughton Creek | Stream | | Northampton | 40 47 20 N | 075 07 09 W |
| Our Lady Help of Christians Church | Church | 6 | Philadelphia | 39 59 12 N | 075 06 19 W |
| Our Lady of Angels College | School | 94 | Delaware | 39 52 28 N | 075 26 25 W |
| Our Lady of Assumption School | School | 128 | Delaware | 40 02 48 N | 075 24 12 W |
| Our Lady of Calvary School | School | 24 | Philadelphia | 40 04 45 N | 074 58 44 W |
| Our Lady of Charity School | School | 30 | Delaware | 39 51 45 N | 075 22 53 W |
| Our Lady of Consolation School | School | 12 | Philadelphia | 40 01 35 N | 075 02 15 W |
| Our Lady of Czestochowa Polish National Shrine | Church | 148 | Bucks | 40 19 09 N | 075 10 44 W |
| Our Lady of Fatima Chapel | Church | 228 | Allegheny | 40 25 47 N | 079 58 34 W |
| Our Lady of Fatima Chapel | Church | 153 | Lebanon | 40 25 27 N | 076 28 19 W |
| Our Lady of Fatima School | School | 35 | Bucks | 40 06 49 N | 074 57 14 W |
| Our Lady of Fatima School | School | 28 | Delaware | 39 54 21 N | 075 18 15 W |
| Our Lady of Good Counsel Elementary School | School | 79 | Bucks | 40 10 15 N | 075 02 35 W |
| Our Lady of Grace Cemetery | Cemetery | 62 | Bucks | 40 09 47 N | 074 56 10 W |
| Our Lady of Grace School | School | 325 | Allegheny | 40 22 21 N | 080 05 01 W |
| Our Lady of Grace School | School | 32 | Bucks | 40 09 17 N | 074 54 54 W |
| Our Lady of Loreto School | School | 19 | Philadelphia | 39 55 32 N | 075 13 41 W |
| Our Lady of Lourdes Cemetery | Cemetery | 311 | Washington | 40 23 16 N | 080 22 33 W |
| Our Lady of Lourdes Church | Church | 148 | Lancaster | 40 06 15 N | 076 05 35 W |
| Our lady of Lourdes High School | School | 284 | Northumberland | 40 47 10 N | 076 35 05 W |
| Our Lady of Lourdes School | School | 67 | Philadelphia | 39 59 05 N | 075 14 53 W |
| Our Lady of Mercy Cemetery | Cemetery | 239 | Columbia | 40 54 16 N | 076 24 54 W |
| Our Lady of Mercy Church | Church | 203 | Erie | 42 10 43 N | 079 57 11 W |
| Our Lady of Mount Carmal Catholic School | School | 124 | Bucks | 40 18 40 N | 075 07 26 W |
| Our Lady of Mount Carmel Cemetery | Cemetery | 606 | Cambria | 40 25 23 N | 078 37 29 W |
| Our Lady of Mount Carmel Cemetery | Cemetery | 272 | Carbon | 40 52 15 N | 075 48 35 W |
| Our Lady of Mount Carmel Church | Church | 130 | Bucks | 40 18 45 N | 075 07 27 W |
| Our Lady of Mount Carmel School | School | 229 | Northampton | 40 52 29 N | 075 12 57 W |
| Our Lady of Peace School | School | 32 | Delaware | 39 52 55 N | 075 20 08 W |
| Our Lady of Perpetual Help School | School | 39 | Delaware | 39 54 25 N | 075 19 17 W |
| Our Lady of Perpetual Help School | School | 109 | Northampton | 40 39 39 N | 075 20 23 W |
| Our Lady of Pompeii Church | Church | 32 | Philadelphia | 40 00 30 N | 075 08 26 W |
| Our Lady of Ransom School | School | 29 | Philadelphia | 40 02 16 N | 075 03 46 W |
| Our Lady of Rosary School | School | 37 | Philadelphia | 39 58 05 N | 075 14 41 W |
| Our Lady of the Blessed Sacrament School | School | 116 | Dauphin | 40 16 49 N | 076 53 33 W |
| Our Lady of Victory Church | Church | 293 | Allegheny | 40 33 09 N | 079 48 26 W |
| Our Lady of Victory Church | Church | 445 | Crawford | 41 49 56 N | 079 40 24 W |
| Our Lady of Victory Church | Church | 268 | Monroe | 41 02 18 N | 075 18 17 W |
| Our Lady of Victory School | School | 33 | Philadelphia | 39 57 52 N | 075 13 42 W |
| Our Mother of Good Counsel Catholic School | School | 127 | Montgomery | 40 01 09 N | 075 18 35 W |
| Our Mother of Sorrows Cemetery | Cemetery | 516 | Lackawanna | 41 36 38 N | 075 33 29 W |
| Our Mother of Sorrows School | School | 36 | Montgomery | 40 06 10 N | 075 20 12 W |
| Our Savior Church | Church | 348 | Allegheny | 40 36 37 N | 080 11 43 W |
| Outcrop | Populated Place | 328 | Fayette | 39 45 57 N | 079 49 30 W |
| Outdoor Country Club of York | Locale | 151 | York | 40 00 36 N | 076 46 35 W |
| Outlet | Populated Place | 424 | Luzerne | 41 20 21 N | 076 03 37 W |
| Outlet City Shopping Mall | Locale | 114 | Lancaster | 40 01 31 N | 076 13 17 W |
| Outlet Station (historical) | Locale | 410 | Luzerne | 41 21 42 N | 076 00 04 W |
| Outwood | Populated Place | 200 | Schuylkill | 40 32 39 N | 076 28 34 W |
| Outwood School | School | 161 | Schuylkill | 40 32 12 N | 076 28 45 W |
| Oval | Populated Place | 247 | Lycoming | 41 09 04 N | 077 10 09 W |
| Oven Run | Stream | | Somerset | 40 07 22 N | 078 55 40 W |
| Over Lake Golf Course | Locale | 231 | Erie | 41 59 10 N | 080 20 50 W |