| OPTAN 1677691 · TMA969654 | Crystal IS, Inc. | 9 Electronics | Registered | 2017 |
| OFTEN 1265831 · TMA875863 | INDUSTRIA DE DISENO TEXTIL, S.A. (INDITEX, S.A.) a Spanish company | 1 Chemicals2 Paints3 Cosmetics+18 | Registered | 2014 |
| OPTAN 0531514 · TMA305701 · design | NATURIN GmbH & CO. | 6 Metal7 Machines9 Electronics+11 | Registered | 1985 |
| OPTANE 1732906 · TMA997154 | INTEL CORPORATION | 9 Electronics | Registered | 2018 |
| OPTAIN 0808641 · TMA473946 | RELIV' INTERNATIONAL, INC. | 32 Beer | Registered | 1997 |
| OBTAIN 2360618 | TOMRA Sorting GmbH | 7 Machines9 Electronics40 Treatment | Pending | 2024 |
| OPTIMUS 2256065 · TMA1277637 · design | Owner not shown | 34 Tobacco | Registered | 2024 |
| OPDENK 2254873 · TMA1273130 | an individual | 26 Sewing | Registered | 2024 |
| OPTIMA3300 2225791 · TMA1252561 | Conair LLC | 9 Electronics | Registered | 2024 |
| OptaMax 2215632 · TMA1233961 | Opta Group LLC | 1 Chemicals | Registered | 2024 |
| OPTIMALIST 2210401 · TMA1241783 | Opscotch Canada Inc. | 18 Leather21 Housewares24 Textiles+1 | Registered | 2024 |
| Optime 2208243 · TMA1280840 | an individual | 6 Metal7 Machines26 Sewing | Registered | 2025 |
| OptimalRx 2200001 · TMA1238488 | an individual | 44 Medical | Registered | 2024 |
| OBODING 2176924 · TMA1227154 | Guangdong Oubang Trading Co. Ltd. | 21 Housewares | Registered | 2024 |
| OPTOMEDIC 2170124 · TMA1248059 · design | Guangdong OptoMedic Technologies Inc. | 10 Medical | Registered | 2024 |
| Opteinics 2169866 · TMA1232344 | an individual | 9 Electronics35 Advertising42 Science+1 | Registered | 2024 |
| OPTINAND 2161450 · TMA1266838 | Western Digital Technologies, Inc. | 9 Electronics | Registered | 2024 |
| OptiOne 2151401 · TMA1185608 | Liebel-Flarsheim Company LLC | 10 Medical | Registered | 2023 |
| Ovation 2149621 · TMA1257702 | AnyDesk Software GmbH | 9 Electronics38 Telecommunications42 Science | Registered | 2024 |
| OPTIMPLUS 2148192 · TMA1187822 | PSP Franchising, LLC | 31 Fresh | Registered | 2023 |
| opTimAIRcook 2146584 · TMA1227953 | CATA Deutschland GmbH | 6 Metal11 Lighting17 Rubber+2 | Registered | 2024 |
| OPTIMOX 2140983 · TMA1245763 | Allergy Research Group LLC | 5 Pharmaceuticals | Registered | 2024 |
| OptiMaster 2126854 · TMA1240944 | LG Display Co., Ltd. | 9 Electronics | Registered | 2024 |
| OPTIMALPRINT 2119319 · TMA1226823 · design | an individual | 9 Electronics16 Paper35 Advertising+2 | Registered | 2024 |
| OPTIMYZE 2101572 · TMA1156502 | Fluid Handling LLC | 9 Electronics | Registered | 2022 |