| ONASSIS 1437292 · TMA905821 | United Colors International Limited | 25 Clothing35 Advertising | Registered | 2015 |
| Omnisexual 2187281 · TMA1232544 | an individual | 24 Textiles | Registered | 2024 |
| ONCOSPACE 2147966 · TMA1256173 | Oncospace, Inc. | 42 Science | Registered | 2024 |
| OMEGAQSTEROLS 2140663 · TMA1181997 | WN Pharmaceuticals Ltd. | 5 Pharmaceuticals | Registered | 2023 |
| ONGOZIG 2058211 · TMA1221079 | Celgene Corporation | 5 Pharmaceuticals | Registered | 2024 |
| oneces 2037698 · TMA1140528 | an individual | 9 Electronics | Registered | 2022 |
| OMgasmic 2031246 · TMA1136517 | an individual | 44 Medical | Registered | 2022 |
| OMZAZI 2029672 · TMA1115475 | an individual | 5 Pharmaceuticals | Registered | 2021 |
| OnKiosk 2009805 · TMA1242213 | Shishi Tongyun Technology (Beijing) Co. Ltd. | 9 Electronics42 Science | Registered | 2024 |
| ONESIXTYTWO 1977181 · TMA1243647 | OneSixtyTwo Digital Capital (Canada) Pte Ltd. | 36 Finance42 Science | Registered | 2024 |
| ONSAGE 1956449 · TMA1191374 | PFIZER INC. | 5 Pharmaceuticals | Registered | 2023 |
| ONCOCIDIN 1902688 · TMA1101669 | NovaVive Inc. | 5 Pharmaceuticals | Registered | 2021 |
| Onsys 1872567 · TMA1042424 | HETTICH MARKETING-UND VERTRIEBS-GMBH & CO. KG | 6 Metal20 Furniture | Registered | 2019 |
| ONECAUSE 1861840 · TMA1086822 | BIDPAL, INC. | 36 Finance | Registered | 2020 |
| ONZISTAN 1829279 · TMA1072532 | GLAXO GROUP LIMITED | 5 Pharmaceuticals | Registered | 2020 |
| ONSAGE 1825869 · TMA1066235 | PFIZER INC. | 5 Pharmaceuticals | Registered | 2019 |
| ONCOSNIPE 1816066 · TMA1018069 | an individual | 9 Electronics42 Science44 Medical | Registered | 2019 |
| OMEGASYN 1812740 · TMA1008769 | ContiTech USA, Inc. | 17 Rubber | Registered | 2018 |
| OMEGASEA 1802949 · TMA998641 | Nature's Way of Canada Limited | 5 Pharmaceuticals | Registered | 2018 |
| ONCOSIM 1795765 · TMA993250 | an individual | 9 Electronics16 Paper35 Advertising+6 | Registered | 2018 |
| ONESIGHT 1794895 · TMA993429 | Agilent Technologies, Inc. | 42 Science | Registered | 2018 |
| OmegaChem 1790963 · TMA989969 | OmegaChem inc. | 1 Chemicals42 Science | Registered | 2018 |
| OMEGACOIL 1771489 · TMA1016018 · design | Owner not shown | 6 Metal | Registered | 2019 |
| OncoShield 1756553 · TMA1064207 | Fresenius Kabi Canada Ltd. | 16 Paper17 Rubber | Registered | 2019 |
| ONCOSHIELD 1756551 · TMA1064208 · design | Fresenius Kabi Canada Ltd. | 16 Paper17 Rubber | Registered | 2019 |