| OSMODERM 1021756 · TMA552045 · design | Bausch Health, Canada Inc. | 5 Pharmaceuticals | Registered | 2001 |
| OSMODERM 1019966 · TMA545913 | Bausch Health, Canada Inc. | 5 Pharmaceuticals | Registered | 2001 |
| OsmoTec 1561734 · TMA893798 | DR. BABOR GMBH & CO. KG | 3 Cosmetics | Registered | 2015 |
| OSMODROL 1276339 · TMA728186 | Northern Innovations Holding Corp. | 5 Pharmaceuticals | Registered | 2008 |
| OSMOTIK 0325728 · TMA183461 | OSMOSIS TECHNOLOGY, INC. (a California corporation) | 7 Machines11 Lighting | Registered | 1972 |
| OceanTears 2205691 · TMA1240230 | an individual | 14 Jewellery | Registered | 2024 |
| OceanAudio 2204384 · TMA1238943 | Alanda INC. | 9 Electronics | Registered | 2024 |
| OZONETECH. 2085424 · TMA1201268 · design | an individual | 1 Chemicals5 Pharmaceuticals9 Electronics+4 | Registered | 2023 |
| OCHENTA 2070972 · TMA1215952 | Guangzhou Shushi Trading Co.Ltd. | 25 Clothing | Registered | 2023 |
| OCEANIDES 1985641 · TMA1128891 · design | Oceanides International Trading Ltd. | 3 Cosmetics | Registered | 2022 |
| OJOND 1942182 · TMA1077354 | an individual | 5 Pharmaceuticals | Registered | 2020 |
| OCYNTIO 1855427 · TMA1076295 | Actelion Pharmaceuticals Ltd. | 5 Pharmaceuticals | Registered | 2020 |
| OSANIT 1812767 · TMA1014478 | an individual | 5 Pharmaceuticals | Registered | 2019 |
| OSSIMTECH 1804321 · TMA988862 | OSSIMTECH INC. | 9 Electronics35 Advertising41 Education+1 | Registered | 2018 |
| OCEANIDES 1793773 · TMA1043143 | Owner not shown | 29 Meat | Registered | 2019 |
| OZZYMAT 1777336 · TMA975075 | CRC Industries, Inc. | 7 Machines | Registered | 2017 |
| OSEntreprendre 1775266 · TMA970008 | OSENTREPRENDRE | 35 Advertising41 Education | Registered | 2017 |
| OZMIET 1775221 · TMA1030648 | Radius Health, Inc. | 5 Pharmaceuticals | Registered | 2019 |
| OEssentials 1773207 · TMA970830 | Canadian Association of Pharmacy in Oncology | 41 Education | Registered | 2017 |
| OKMED 1759337 · TMA971763 · design | Okmed Pharmaceuticals inc. | 5 Pharmaceuticals | Registered | 2017 |
| OXYNET 1734739 · TMA948753 | Cartier Chemicals Ltd | 1 Chemicals3 Cosmetics | Registered | 2016 |
| OCUMETICS 1697701 · TMA1035931 | Ocumetics Technology Corp. | 9 Electronics10 Medical | Registered | 2019 |
| OXANTI 1544120 · TMA837166 | Owner not shown | 30 Coffee | Registered | 2012 |
| Oxymat 1501436 · TMA853466 | an individual | 9 Electronics10 Medical | Registered | 2013 |
| OXYMATIC 1464485 · TMA842470 | Owner not shown | 9 Electronics11 Lighting | Registered | 2013 |