Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Old Tand P Lake | Reservoir | 111 | Bowie | 33 28 06 N | 094 26 43 W |
| Old Tank | Reservoir | 299 | Archer | 33 42 14 N | 098 31 24 W |
| Old Tank | Reservoir | 1639 | Jeff Davis | 30 50 18 N | 104 05 01 W |
| Old Tank Canyon | Valley | | Jeff Davis | 30 51 06 N | 104 02 50 W |
| Old Tarrant Church | Church | 144 | Hopkins | 33 11 54 N | 095 35 17 W |
| Old Taylor County Courthouse and Jail | Building | 579 | Taylor | 32 17 10 N | 099 49 37 W |
| Old Tenmile Creek | Stream | | Ellis | 32 28 51 N | 096 31 02 W |
| Old Terminal | Locale | 0 | Nueces | 27 54 54 N | 097 06 14 W |
| Old Terrell City Lake | Reservoir | 145 | Kaufman | 32 44 01 N | 096 14 46 W |
| Old Town Cemetery | Cemetery | 48 | Brooks | 27 11 55 N | 098 13 11 W |
| Old Town Lake | Lake | 0 | Calhoun | 28 33 15 N | 096 32 05 W |
| Old Town Windmill | Locale | 47 | Brooks | 27 11 36 N | 098 13 11 W |
| Old Tram Hiking Trail | Trail | 80 | Houston | 31 27 59 N | 095 06 43 W |
| Old Trinity Cemetery | Cemetery | 168 | Tarrant | 32 46 19 N | 097 20 47 W |
| Old Trinity University - Texas Hall | School | 192 | Limestone | 31 44 39 N | 096 32 44 W |
| Old Troy Cemetery | Cemetery | 212 | Bell | 31 13 55 N | 097 18 21 W |
| Old Tulosa Ranch Site | Locale | 5 | Cameron | 25 56 26 N | 097 18 26 W |
| Old Turkey Windmill | Locale | 44 | Live Oak | 28 09 03 N | 098 00 35 W |
| Old Union | Populated Place | 99 | Bowie | 33 20 23 N | 094 27 57 W |
| Old Union | Populated Place | 140 | Limestone | 31 24 32 N | 096 24 59 W |
| Old Union | Populated Place | 187 | Tarrant | 32 55 33 N | 097 07 38 W |
| Old Union | Populated Place | 116 | Titus | 33 11 15 N | 094 54 50 W |
| Old Union Cemetery | Cemetery | 99 | Bowie | 33 20 32 N | 094 27 57 W |
| Old Union Cemetery | Cemetery | 215 | Collin | 33 19 25 N | 096 46 45 W |
| Old Union Cemetery | Cemetery | 128 | Leon | 31 22 14 N | 096 04 14 W |
| Old Union Church | Church | 91 | Angelina | 31 19 08 N | 094 46 28 W |
| Old Union Church | Church | 133 | Limestone | 31 24 24 N | 096 24 20 W |
| Old Union Church | Church | 134 | Nacogdoches | 31 37 28 N | 094 44 36 W |
| Old Union Hill Cemetery | Cemetery | 114 | Cass | 33 02 34 N | 094 30 07 W |
| Old United States Post Office and Courts Building | Building | 60 | Marion | 32 45 21 N | 094 20 46 W |
| Old Uribaņo | Locale | 94 | Zapata | 26 55 56 N | 099 20 47 W |
| Old Valera Cemetery | Cemetery | 568 | Coleman | 31 45 44 N | 099 33 12 W |
| Old Valley Mills Cemetery | Cemetery | 187 | Bosque | 31 40 25 N | 097 28 23 W |
| Old Vat Windmill | Locale | 46 | Goliad | 28 35 21 N | 097 20 60 W |
| Old Victoria County Courthouse | Building | 29 | Victoria | 28 47 59 N | 097 00 23 W |
| Old Walker Well | Well | 1201 | Culberson | 31 36 03 N | 104 23 57 W |
| Old Waverly | Populated Place | 128 | San Jacinto | 30 31 45 N | 095 21 10 W |
| Old Waverly Cemetery | Cemetery | 122 | Walker | 30 32 01 N | 095 21 51 W |
| Old Waverly Church | Church | 131 | San Jacinto | 30 32 01 N | 095 21 05 W |
| Old Well | Well | 673 | Crockett | 30 28 05 N | 101 33 09 W |
| Old Well Windmill | Locale | 16 | Kenedy | 27 07 47 N | 097 50 24 W |
| Old Well Windmill | Locale | 867 | Reeves | 31 05 51 N | 103 26 46 W |
| Old Wellington Cemetery | Cemetery | 620 | Collingsworth | 34 51 44 N | 100 12 26 W |
| Old West Texas Utilities Company | Building | 491 | Jones | 32 56 44 N | 099 48 07 W |
| Old White Windmill | Locale | 554 | Val Verde | 30 02 44 N | 100 53 32 W |
| Old Wildcat Windmill | Locale | 1137 | Oldham | 35 31 50 N | 102 49 60 W |
| Old Windmill | Locale | 639 | Gillespie | 30 26 08 N | 099 16 34 W |
| Old Windmill | Locale | 712 | Real | 29 58 48 N | 099 43 58 W |
| Old Wooden Town Windmill | Locale | 543 | King | 33 32 24 N | 100 17 53 W |
| Old Word Ranch | Locale | 1678 | Brewster | 30 23 30 N | 103 08 26 W |
| Old X Ranch | Locale | 823 | Reeves | 31 16 16 N | 103 18 02 W |
| Old Yegua Creek | Stream | | Washington | 30 20 37 N | 096 25 40 W |
| Old Zachman Tank | Reservoir | 226 | Zavala | 28 50 04 N | 099 35 07 W |
| Old Zion Cemetery | Cemetery | 148 | Freestone | 31 28 09 N | 096 09 50 W |
| Old Zion Cemetery | Cemetery | 104 | Houston | 31 24 56 N | 095 11 22 W |
| Old Zion Creek | Stream | | Houston | 31 26 35 N | 095 12 32 W |
| Olde Cemetery | Cemetery | 243 | Bosque | 31 37 60 N | 097 31 04 W |
| Olden | Populated Place | 475 | Eastland | 32 25 08 N | 098 45 03 W |
| Oldenburg | Populated Place | 117 | Fayette | 29 58 36 N | 096 45 54 W |
| Oldham | Populated Place | 135 | Dallas | 32 52 21 N | 096 52 52 W |
| Oldham | Populated Place | 119 | Houston | 31 23 56 N | 095 29 01 W |
| Oldham | Populated Place | 62 | Tyler | 30 44 29 N | 094 14 03 W |
| Oldham Avenue Historic District | Locale | 173 | Ellis | 32 23 22 N | 096 50 39 W |
| Oldham Branch | Stream | | Houston | 31 14 14 N | 095 22 04 W |
| Oldham Cemetery | Cemetery | 224 | Somervell | 32 15 09 N | 097 41 55 W |
| Oldham Church | Church | 79 | Burleson | 30 34 28 N | 096 34 45 W |
| Oldham County | Civil | 1127 | Oldham | 35 25 00 N | 102 36 02 W |
| Oldham County Airport | Airport | 1214 | Oldham | 35 13 55 N | 102 23 58 W |
| Oldham Hollow | Valley | 415 | McCulloch | 31 25 22 N | 099 06 09 W |
| Oldham Lane Church of Christ | Church | 542 | Taylor | 32 23 07 N | 099 42 29 W |
| Oldham Oil Field | Oilfield | 339 | Archer | 33 32 00 N | 098 46 39 W |
| Olds Creek | Stream | | Jeff Davis | 30 36 50 N | 103 58 36 W |
| Olds Slough | Stream | | Live Oak | 28 27 04 N | 098 08 11 W |
| Olds Tank | Reservoir | 1701 | Jeff Davis | 30 40 13 N | 104 00 27 W |
| Oldtown Cemetery | Cemetery | 233 | Wise | 33 11 50 N | 097 46 51 W |
| Ole and Ann Pierson Farm | Locale | 282 | Bosque | 31 45 38 N | 097 43 06 W |
| Ole and Elizabeth Finstad Homesite | Locale | 267 | Bosque | 31 43 55 N | 097 43 37 W |
| Ole Doc Branch | Stream | | Newton | 31 07 18 N | 093 48 26 W |
| Oleson Elementary School | School | 22 | Harris | 29 54 17 N | 095 19 28 W |
| Oleson School | School | 22 | Harris | 29 54 17 N | 095 19 26 W |
| Oletha | Populated Place | 145 | Limestone | 31 21 31 N | 096 24 47 W |
| Oleys Creek | Stream | | Stonewall | 32 59 59 N | 100 08 22 W |
| Olfen | Populated Place | 522 | Runnels | 31 36 35 N | 099 57 38 W |
| Olga | Locale | 320 | Bexar | 29 33 22 N | 098 35 17 W |
| Olin | Populated Place | 388 | Hamilton | 31 52 39 N | 098 06 25 W |
| Olin E Teague Veterans Center | Building | 207 | Bell | 31 04 34 N | 097 20 49 W |
| Olinick Dam | Dam | 104 | Karnes | 29 02 07 N | 097 57 55 W |
| Olinick Reservoir | Reservoir | 104 | Karnes | 29 02 07 N | 097 57 55 W |
| Oliphant House | Building | 72 | Sabine | 31 28 05 N | 093 45 24 W |
| Oliphant Ranch | Locale | 237 | Zavala | 28 59 18 N | 099 59 46 W |
| Oliphant-Walker House | Building | 187 | Travis | 30 18 12 N | 097 44 06 W |
| Olivares Cemetery | Cemetery | 69 | Starr | 26 42 42 N | 098 24 13 W |
| Olivares Elementary School | School | 198 | Bexar | 29 19 45 N | 098 32 35 W |
| Olivarez | Populated Place | 20 | Hidalgo | 26 13 42 N | 097 59 32 W |
| Olivarez Colonia | Populated Place | 70 | Starr | 26 23 32 N | 098 50 07 W |
| Olivarez Number 1 Colonia | Populated Place | 19 | Hidalgo | 26 11 11 N | 097 58 49 W |
| Olivarez Number 10 Colonia | Populated Place | 19 | Hidalgo | 26 13 27 N | 097 57 59 W |
| Olivarez Number 15 Colonia | Populated Place | 21 | Hidalgo | 26 14 00 N | 098 00 05 W |
| Olivarez Number 17 Colonia | Populated Place | 20 | Hidalgo | 26 14 00 N | 097 59 14 W |
| Olivarez Number 18 Colonia | Populated Place | 19 | Hidalgo | 26 15 19 N | 097 58 27 W |
| Olivarez Number 2 Colonia | Populated Place | 19 | Hidalgo | 26 12 44 N | 097 59 07 W |
| Olivarez Number 3 Colonia | Populated Place | 20 | Hidalgo | 26 12 33 N | 097 59 07 W |
| Olivarez Number 4 Colonia | Populated Place | 18 | Hidalgo | 26 13 38 N | 097 57 41 W |
| Olivarez Number 5 Colonia | Populated Place | 22 | Hidalgo | 26 08 50 N | 097 58 35 W |
| Olivarez Number 6 Colonia | Populated Place | 18 | Hidalgo | 26 12 59 N | 097 59 07 W |
| Olivarez Number 7 Colonia | Populated Place | 19 | Hidalgo | 26 15 30 N | 097 58 31 W |
| Olivarez Number 8 Colonia | Populated Place | 21 | Hidalgo | 26 15 23 N | 097 59 29 W |
| Olivarez Number 9 Colonia | Populated Place | 20 | Hidalgo | 26 15 33 N | 097 58 42 W |
| Olive Bethel Baptist Church | Church | 12 | Liberty | 30 10 55 N | 094 45 53 W |
| Olive Branch | Stream | | Burnet | 30 54 37 N | 098 02 04 W |