| OSLIA 2301452 | MANTRA PHARMA INC. | 5 Pharmaceuticals10 Medical | Pending | 2023 |
| OSLO 0742366 · TMA434852 | MARSHALL-BROWNING INTERNATIONAL CORPORATION, A CORPORATION OF DELAWARE | 14 Jewellery | Registered | 1994 |
| OSL. 2294272 · design | OSL Retail Services, Inc. | 35 Advertising | Pending | 2023 |
| OSL 2294268 | OSL Retail Services, Inc. | 35 Advertising | Pending | 2023 |
| OCLI 2209508 | Viavi Solutions Inc. | 2 Paints9 Electronics | Pending | 2022 |
| OCLI 2203469 · design | Viavi Solutions Inc. | 2 Paints9 Electronics | Pending | 2022 |
| OJOLI 1831430 · TMA1055720 | Shamir Optical Industry Ltd. | 9 Electronics37 Construction40 Treatment+1 | Registered | 2019 |
| OSELA 1812616 · TMA1010209 | OSELA INC. | 9 Electronics | Registered | 2018 |
| OSLYA 2316273 | MANTRA PHARMA INC. | 5 Pharmaceuticals | Pending | 2024 |
| OKULI 2084547 · design | Leadership Inspirant inc. | 35 Advertising41 Education | Pending | 2021 |
| OKLA 2251459 · TMA1270123 · design | Owner not listed | 12 Vehicles | Registered | 2024 |
| OGLO 2194646 · TMA1235154 | 2301114 Alberta Ltd. | 9 Electronics11 Lighting | Registered | 2024 |
| OGL 2165861 · TMA1213390 · design | Guangzhou Dongchen Zhizao Supply Chain Co. LTD. | 25 Clothing | Registered | 2023 |
| OXILIA 2047094 · TMA1283895 · design | OXILIA INC. | 35 Advertising | Registered | 2025 |
| OQL 1864732 · TMA1068895 | an individual | 7 Machines9 Electronics12 Vehicles | Registered | 2020 |
| OCL 1821855 · TMA1009278 · design | OCL Group Inc | 35 Advertising37 Construction39 Transport+2 | Registered | 2018 |
| OXELIA 1711238 · TMA1037630 | Xylem Water Solutions U.S.A. Inc. | 6 Metal9 Electronics11 Lighting+2 | Registered | 2019 |
| OCALIO 1683538 · TMA972088 | SOLVAY ACETOW GMBH | 1 Chemicals17 Rubber | Registered | 2017 |
| OGSL 0918296 | Her Majesty the Queen in Right of Canada, as represented by the the Minister of Fisheries and Oceans | All goods and services | Protected | 2008 |
| OJL 0469601 · TMA278522 · design | ORIGINAL JEWELLERY LIMITED | 14 Jewellery | Registered | 1983 |
| OZLO 2359036 | Drowsy Digital, Inc. | 9 Electronics10 Medical42 Science+1 | Pending | 2023 |
| OSHYLE 2329799 | Owner not listed | 28 Toys | Pending | 2024 |
| OSWELL 2259910 · design | Owner not listed | 9 Electronics | Pending | 2023 |
| OCLU 1975629 · design | OCLU LIMITED | 9 Electronics35 Advertising41 Education | Pending | 2019 |