| OLIS 1296872 · TMA688449 | CACEIS Bank (Société anonyme) | 9 Electronics35 Advertising36 Finance | Registered | 2007 |
| OLYS 1240419 · TMA717921 | an individual | 29 Meat30 Coffee32 Beer | Registered | 2008 |
| OLC 1705602 · TMA950069 | Calgon Carbon Corporation, a Delaware corporation | 1 Chemicals | Registered | 2016 |
| OLG 1291756 · TMA736827 · design | Ontario Lottery and Gaming Corporation | 41 Education | Registered | 2009 |
| OLG 1291751 · TMA736387 | Ontario Lottery and Gaming Corporation | 41 Education | Registered | 2009 |
| OLC 2048207 · design | an individual | 9 Electronics10 Medical | Pending | 2020 |
| OLG 0919932 · design | Ontario Lottery and Gaming Corporation | 1 Chemicals2 Paints3 Cosmetics+42 | Pending | 2011 |
| OLG 0919866 | Ontario Lottery and Gaming Corporation | 1 Chemicals2 Paints3 Cosmetics+42 | Pending | 2010 |
| OLEIS 1899154 · TMA1085740 | Owner not shown | 11 Lighting | Registered | 2020 |
| OILES 1721054 · TMA957644 · design | Oiles Corporation | 6 Metal7 Machines9 Electronics+4 | Registered | 2016 |
| OILES 1721051 · TMA957531 · design | Oiles Corporation | 6 Metal7 Machines9 Electronics+4 | Registered | 2016 |
| OILES 1412211 · TMA765177 | Oiles Corporation | 6 Metal7 Machines8 Hand+2 | Registered | 2010 |
| Ollse 2302495 | Shenzhen Xinchuanghui Trading Co. Ltd. | 21 Housewares | Pending | 2023 |
| OLLOS 2272541 | an individual | 29 Meat30 Coffee | Pending | 2023 |
| OWALGO 2249311 · TMA1268659 | Owner not listed | 20 Furniture | Registered | 2024 |
| Oillase 2212809 · TMA1243168 | Fuzhou feibao electronic commerce co., LTD | 3 Cosmetics | Registered | 2024 |
| OLEICO 2199898 · TMA1241248 | Owner not shown | 29 Meat | Registered | 2024 |
| Oligei 2177206 · TMA1252315 | an individual | 16 Paper | Registered | 2024 |
| OliX 2170167 · TMA1262724 | OliX Pharmaceuticals, Inc. | 5 Pharmaceuticals42 Science | Registered | 2024 |
| OYLZG 2119575 · TMA1186398 · design | Shenzhen Yilianzhonggou Trading Co. Ltd. | 12 Vehicles28 Toys | Registered | 2023 |
| ouluoqi 2079802 · TMA1240873 | an individual | 9 Electronics | Registered | 2024 |
| OULUCCI 1990052 · TMA1128920 | Shenzhen Ouluoqi Technology Co. Ltd. | 9 Electronics | Registered | 2022 |
| OILAX 1963288 · TMA1137947 · design | Shenzhen Hengruisi Industrial Co., Ltd. | 10 Medical34 Tobacco | Registered | 2022 |
| OWLEEZ 1926216 · TMA1125238 | Spin Master Ltd. | 28 Toys | Registered | 2022 |
| OLIQ 1918275 · TMA1109065 | MIGROS-GENOSSENSCHAFTS-BUND | 5 Pharmaceuticals | Registered | 2021 |