| ONGUARD 1920193 · TMA1153439 | Chewy, Inc. | 5 Pharmaceuticals | Registered | 2022 |
| ONGUARD 1804675 · TMA996980 | Hampton Rubber Company | 35 Advertising37 Construction42 Science | Registered | 2018 |
| ONESORT 1744693 · TMA970751 | DMT Solutions Global Corporation, a Delaware corporation | 9 Electronics | Registered | 2017 |
| ONGUARD 1647173 · TMA978506 | Dunlop Protective Footwear USA, LLC | 9 Electronics25 Clothing | Registered | 2017 |
| ONGUARD 1647168 · TMA978507 · design | Dunlop Protective Footwear USA, LLC | 9 Electronics25 Clothing | Registered | 2017 |
| ONGUARD 1546882 · TMA835829 | an individual | 9 Electronics | Registered | 2012 |
| ONGUARD 1527022 · TMA903570 | Sigma Loyalty Group, Inc. | 35 Advertising36 Finance42 Science+1 | Registered | 2015 |
| ONGUARD 1443992 · TMA787717 | Riverain Technologies, LLC | 9 Electronics10 Medical | Registered | 2011 |
| ONECARE 1350004 · TMA787513 | Bradshaw Canada Holdings, Inc. | 3 Cosmetics20 Furniture21 Housewares+1 | Registered | 2011 |
| ONGUARD 0888277 · TMA533434 | DIONEX CORPORATION | 9 Electronics | Registered | 2000 |
| ONGUARD 0815386 · TMA527491 | PURAFIL, INC. | 9 Electronics | Registered | 2000 |
| ONECARE 2348969 | Owner not listed | 42 Science | Pending | 2024 |
| ONECARD 2347756 · design | Athbhreith Pty Ltd | 9 Electronics35 Advertising41 Education+1 | Pending | 2024 |
| Onecare 2329041 | Owner not listed | 42 Science | Pending | 2024 |
| ONGUARD 2256296 | UR-CAN Inc. | 5 Pharmaceuticals21 Housewares | Pending | 2023 |
| ONECARD 2130513 | O'Neil Digital Solutions, LLC (a California limited liability company) | 42 Science | Pending | 2021 |
| ONECARD 2130512 · design | O'Neil Digital Solutions, LLC (a California limited liability company) | 42 Science | Pending | 2021 |
| ONESEARCH 2099904 · TMA1154377 · design | Yahoo Inc. | 42 Science | Registered | 2022 |
| OMNISHARE 2081245 · TMA1150612 | Market Track, LLC | 9 Electronics35 Advertising42 Science | Registered | 2022 |
| OMNICORE 2164076 · TMA1197174 | IW Apparel, LLC | 9 Electronics | Registered | 2023 |
| ONCUR 2103275 · TMA1211836 · design | Shanghai Qiran Biological Technology Co. Ltd. | 3 Cosmetics | Registered | 2023 |
| onegrus 2101695 · TMA1175818 | Shenzhen Tomtoc technology Co. Ltd. | 9 Electronics18 Leather20 Furniture | Registered | 2023 |
| OMOSHIROI 2077332 · TMA1178877 | TRIAD Inc. | 16 Paper | Registered | 2023 |
| ONCXERNA 2069939 · TMA1210542 · design | OncXerna Therapeutics, Inc. | 1 Chemicals5 Pharmaceuticals42 Science | Registered | 2023 |
| ONCXERNA 2063453 · TMA1209408 | OncXerna Therapeutics, Inc. | 1 Chemicals5 Pharmaceuticals42 Science | Registered | 2023 |