| OvuGel 1385224 · TMA811782 | UNITED ANIMAL HEALTH, INC. | 5 Pharmaceuticals | Registered | 2011 |
| OVAXCALA 2247395 · TMA1267178 | Owner not listed | 5 Pharmaceuticals | Registered | 2024 |
| Opaceluuk 2220250 · TMA1247019 | an individual | 21 Housewares | Registered | 2024 |
| OPZELURA 2186625 · TMA1186829 · design | Incyte Holdings Corporation | 5 Pharmaceuticals16 Paper44 Medical | Registered | 2023 |
| OPSIAL 2176224 · TMA1272558 · design | DESCOURS ET CABAUD SA | 9 Electronics25 Clothing | Registered | 2024 |
| OUVISLITE 2164751 · TMA1214477 | Shenzhen Xialin Technology Co. Ltd | 9 Electronics | Registered | 2023 |
| OPZELURA 2143507 · TMA1186690 | Incyte Holdings Corporation | 5 Pharmaceuticals16 Paper44 Medical | Registered | 2023 |
| OFFICEALLY 2045552 · TMA1123967 | Headsets.com, Inc. | 9 Electronics | Registered | 2022 |
| OVHcloud 2018307 · TMA1156101 | OVH | 35 Advertising42 Science45 Legal | Registered | 2022 |
| OPSLEVEL 1964659 · TMA1276706 | J/K Labs Inc. | 9 Electronics42 Science | Registered | 2024 |
| OVHcloud 1893577 · TMA1098928 | OVH | 9 Electronics35 Advertising36 Finance+5 | Registered | 2021 |
| OPCLEAR 1808955 · TMA1004997 | Cipher Surgical Limited | 10 Medical37 Construction41 Education | Registered | 2018 |
| OPSHIELD 1747159 · TMA1017908 | GENERAL ELECTRIC COMPANY | 9 Electronics42 Science | Registered | 2019 |
| OVACALC 1742504 · TMA1003707 | Aspira Women's Health Inc. | 9 Electronics42 Science44 Medical | Registered | 2018 |
| OPSIAL 1735901 · TMA966256 · design | DESCOURS ET CABAUD SA | 9 Electronics25 Clothing | Registered | 2017 |
| OPSIAL 1735900 · TMA966255 | DESCOURS ET CABAUD SA | 9 Electronics25 Clothing | Registered | 2017 |
| OFISHL 1735736 · TMA1006869 | an individual | 25 Clothing28 Toys | Registered | 2018 |
| OPGAL 1591735 · TMA901493 | OPGAL OPTRONIC INDUSTRIES LTD. | 9 Electronics | Registered | 2015 |
| OPUSLICENCE 1461592 · TMA799840 · design | OPUSLICENCE GROUP INC./ GROUPE OPUSLICENCE INC. | 35 Advertising37 Construction | Registered | 2011 |
| OPCELL 1259354 · TMA657863 | SANWA KAKO KABUSHIKI KAISHA, a corporation of Japan | 17 Rubber | Registered | 2006 |
| OFFICELINK 1245815 · TMA670379 · design | Quantum Lifecycle Partners LP | 35 Advertising | Registered | 2006 |
| OVISLINK 1238851 · TMA659227 · design | OVISLINK (CANADA) INC. | 9 Electronics | Registered | 2006 |
| OVICOLLAR 0709946 · TMA436544 | an individual | 3 Cosmetics5 Pharmaceuticals | Registered | 1994 |
| OPAZIL 0501619 · TMA295195 | an individual | 1 Chemicals | Registered | 1984 |
| OPACOLOR 0467936 · TMA271523 | BPSI Holdings LLC | 2 Paints5 Pharmaceuticals | Registered | 1982 |