| OPENDO 1540461 · TMA885738 | an individual | 9 Electronics16 Paper35 Advertising+4 | Registered | 2014 |
| opendi 1513427 · TMA833549 | an individual | 35 Advertising41 Education | Registered | 2012 |
| Openatey 2216098 · TMA1245393 | Guangzhou Kexing Trading Co., Ltd. | 25 Clothing | Registered | 2024 |
| OPENTUBE 1901257 · TMA1128775 | Amazon Technologies, Inc. | 9 Electronics35 Advertising38 Telecommunications+3 | Registered | 2022 |
| OPENID 1727604 · TMA1059867 | Open ID Foundation | 35 Advertising41 Education42 Science | Registered | 2019 |
| OPENEDGE 1718247 · TMA1024874 | Global Payments Inc. | 36 Finance | Registered | 2019 |
| OPENDIME 1715344 · TMA1001723 | Coinkite Inc. | 9 Electronics25 Clothing36 Finance+5 | Registered | 2018 |
| OPENDOOR 1485770 · TMA832257 | Cook Medical Technologies LLC | 44 Medical | Registered | 2012 |
| OPENID 1325418 · TMA710722 | OpenID Foundation | 42 Science | Registered | 2008 |
| OPENEDGE 1122734 · TMA597518 | PROGRESS SOFTWARE CORPORATION | 9 Electronics | Registered | 2003 |
| OPENTRAIN 0816208 · TMA564392 | THE INFORMATION REFINERY (CANADA) INC. | 9 Electronics16 Paper35 Advertising+3 | Registered | 2002 |
| OPENDEL 2270489 · design | Owner not listed | 1 Chemicals5 Pharmaceuticals42 Science | Pending | 2023 |
| OPENATOM 2104725 · design | OPENATOM FOUNDATION | 9 Electronics35 Advertising36 Finance+3 | Pending | 2020 |
| OPENMEET 2193848 · TMA1271172 · design | SHOKZ (SINGAPORE) PTE. LTD. | 9 Electronics | Registered | 2024 |
| OPIANT 2173498 · TMA1198227 | Opiant Pharmaceuticals, Inc. | 5 Pharmaceuticals | Registered | 2023 |
| OPIANT 2173497 · TMA1198226 · design | Opiant Pharmaceuticals, Inc. | 5 Pharmaceuticals | Registered | 2023 |
| OPENDOTS 2151098 · TMA1192925 · design | SHOKZ (SINGAPORE) PTE. LTD. | 9 Electronics | Registered | 2023 |
| OVENTURE 2014662 · TMA1260866 | The Big O, LLC | 14 Jewellery18 Leather35 Advertising | Registered | 2024 |
| OPENTIME 2004856 · TMA1264875 | an individual | 42 Science | Registered | 2024 |
| OVINTIV 2001221 · TMA1281899 | Ovintiv Trademarks Inc. | 4 Oils35 Advertising37 Construction+3 | Registered | 2025 |
| OPENTEMP 1999111 · TMA1258825 · design | Opentemp Recruiting Inc. | 9 Electronics35 Advertising | Registered | 2024 |
| OVENTE 1981564 · TMA1116537 | Topnet, Inc. | 7 Machines11 Lighting20 Furniture+1 | Registered | 2021 |
| OPENTAP 1958105 · TMA1220061 · design | Keysight Technologies, Inc. | 9 Electronics42 Science | Registered | 2024 |
| OVENTUS 1956541 · TMA1165175 | OPEN AIRWAY DENTAL SOLUTIONS LTD. | 10 Medical40 Treatment | Registered | 2023 |
| OPENTAP 1943549 · TMA1220060 | Keysight Technologies, Inc. | 9 Electronics42 Science | Registered | 2024 |