| OCTOPRE 2089311 · TMA1195339 | Focusrite Audio Engineering Limited | 9 Electronics15 Musical | Registered | 2023 |
| Osteopal 1265929 · TMA786916 | HERAEUS MEDICAL GmbH | 5 Pharmaceuticals10 Medical | Registered | 2011 |
| OSTEOPAK 0525462 · TMA333020 | Biomet Manufacturing, LLC | 10 Medical | Registered | 1987 |
| Ostéopetit 1740801 · TMA948920 | an individual | 44 Medical | Registered | 2016 |
| OSTEOFORTE 1128280 · TMA695400 | an individual | 5 Pharmaceuticals | Registered | 2007 |
| OSTEOBRUSH 2247110 | OsteoRemedies, LLC | 10 Medical | Pending | 2023 |
| Osteopractic 1546715 · TMA847408 | an individual | 41 Education | Registered | 2013 |
| Osteopractor 1546227 · TMA847409 | an individual | 41 Education | Registered | 2013 |
| OSTEOVANT 1941438 · TMA1136971 | Roivant Sciences GmbH | 5 Pharmaceuticals42 Science44 Medical | Registered | 2022 |
| OCTOBRE 1541705 · TMA883882 | VERGER R. & J. BOUCHARD INC. | 32 Beer | Registered | 2014 |
| OSTEOBOND 0664935 · TMA464108 | Zimmer, Inc. | 1 Chemicals10 Medical | Registered | 1996 |
| OSTEOFIT 0910278 | CHILDREN'S & WOMEN'S HEALTH CENTRE OF BRITISH COLUMBIA | 1 Chemicals2 Paints3 Cosmetics+42 | Pending | 1999 |
| OsteoHybrid 1699320 · TMA927210 | OsteoReady, LLC | 10 Medical | Registered | 2016 |
| OSTEOFILLER 1678864 · TMA1039511 | Owner not shown | 5 Pharmaceuticals | Registered | 2019 |
| OCTOPUCE 2243490 · TMA1277568 · design | Sommex communication Inc. | 42 Science | Registered | 2024 |
| 8 OCTOFLORE 2220435 · TMA1253784 · design | Groupe Octoflore Inc | 3 Cosmetics | Registered | 2024 |
| Octobox 2190279 · TMA1233706 | PHILLIPS BREWING LIMITED PARTNERSHIP | 32 Beer | Registered | 2024 |
| OCTOPLATINUM 2072251 · TMA1280357 | DURADRIVE SYSTEMS INTERNATIONAL INC. | 1 Chemicals6 Metal | Registered | 2025 |
| OCTUBEE 2070420 · TMA1280288 | an individual | 21 Housewares | Registered | 2025 |
| OCTOPUS 1996202 · TMA1239324 · design | CMP Group Limited | 7 Machines12 Vehicles | Registered | 2024 |
| OCTAVE 1946362 · TMA1254334 | Owner not shown | 25 Clothing35 Advertising | Registered | 2024 |
| OCTAVE 1931736 · TMA1122599 | SIERRA WIRELESS, INC. | 38 Telecommunications42 Science | Registered | 2022 |
| OCTAVE 1930975 · TMA1115718 | Octave Bioscience, Inc. | 5 Pharmaceuticals9 Electronics42 Science+1 | Registered | 2021 |
| OCTAVE 1926213 · TMA1118765 | SIERRA WIRELESS, INC. | 9 Electronics42 Science | Registered | 2022 |
| OCTOPUS 1923868 · TMA1123723 | CommScope Technologies LLC | 9 Electronics17 Rubber | Registered | 2022 |