| OSISENSE 1411331 · TMA761743 | an individual | 9 Electronics | Registered | 2010 |
| OXYGENEO 2095428 · TMA1192569 | Pollogen Ltd. | 3 Cosmetics | Registered | 2023 |
| OXYGENEO 1866423 · TMA1032944 | Pollogen Ltd. | 10 Medical | Registered | 2019 |
| OXIGEN 1711792 · TMA960627 | Flair Flexible Packaging Corporation (USA) | 16 Paper | Registered | 2017 |
| OXYGENOS 2275659 · design | OnePlus Technology (Shenzhen) Co. Ltd. | 9 Electronics | Pending | 2023 |
| OccasionALL 2219100 · TMA1226385 | Prime Line Packaging, Inc. | 16 Paper | Registered | 2024 |
| Okycan 2148527 · TMA1203099 | Guangzhou Bosi International Trading Co. Ltd. | 21 Housewares | Registered | 2023 |
| OGASAMI 2122914 · TMA1256125 | Shenzhen Hi Wang Daoxing Technology Innovation Co. Ltd. | 9 Electronics | Registered | 2024 |
| OCCASION 2121671 · TMA1197706 | KOHLER CO. | 11 Lighting | Registered | 2023 |
| OXYGENICS 2054124 · TMA1168194 | ETL, LLC | 11 Lighting | Registered | 2023 |
| OXYGENI 2019186 · TMA1264978 | Electrochemical Oxygen Concepts, Inc. | 10 Medical | Registered | 2024 |
| OXYGENI 2019185 · TMA1264977 | Electrochemical Oxygen Concepts, Inc. | 41 Education | Registered | 2024 |
| OCCASION 2019043 · TMA1263754 | KOHLER CO. | 6 Metal11 Lighting20 Furniture+1 | Registered | 2024 |
| OCCASNEO 2015139 · TMA1114152 | an individual | 5 Pharmaceuticals | Registered | 2021 |
| OXYGEN 8 1979169 · TMA1226617 | Owner not shown | 44 Medical | Registered | 2024 |
| OCCASIONS 1928392 · TMA1110205 | Sunbeam Products, Inc. | 11 Lighting | Registered | 2021 |
| OCUSYNC 1872313 · TMA1078263 · design | SZ DJI TECHNOLOGY Co. Ltd. | 9 Electronics | Registered | 2020 |
| OCUSYNC 1824434 · TMA1005634 | SZ DJI TECHNOLOGY Co. Ltd. | 9 Electronics | Registered | 2018 |
| Oxygheme 1796942 · TMA993519 | Naturo Aid Pharmaceutical Inc. | 5 Pharmaceuticals | Registered | 2018 |
| OXYGENI 1788892 · TMA1063754 · design | Electrochemical Oxygen Concepts, Inc. | 44 Medical | Registered | 2019 |
| OXYGENI 1788891 · TMA1063756 · design | Electrochemical Oxygen Concepts, Inc. | 41 Education | Registered | 2019 |
| OXYGENI 1788890 · TMA1063753 · design | Electrochemical Oxygen Concepts, Inc. | 10 Medical | Registered | 2019 |
| Ôcuisine 1747587 · TMA958114 | Owner not shown | 21 Housewares | Registered | 2016 |
| OXYGENICS 1727150 · TMA959375 | Oxygen Biological Inc. | 3 Cosmetics5 Pharmaceuticals21 Housewares+2 | Registered | 2017 |
| OXYGENCEUTICALS 1706652 · TMA1084156 · design | an individual | 3 Cosmetics10 Medical | Registered | 2020 |