| OSSID 0725937 · TMA432411 | OSSID LLC | 7 Machines9 Electronics16 Paper | Registered | 1994 |
| OKKID 2032173 · TMA1142734 · design | SHENZHEN CHUANGQUAN ELECTRONICS CO. LTD | 9 Electronics | Registered | 2022 |
| OCAD 0717232 · TMA429549 | an individual | 9 Electronics | Registered | 1994 |
| OXOID 0248532 · TMA118717 | OXOID INC. | 5 Pharmaceuticals | Registered | 1960 |
| OECD 0974535 · design | ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT / ORGANISATION DE COOPÉRATION ET DE DÉVELOPPEMENT ÉCONOMIQUES | 1 Chemicals2 Paints3 Cosmetics+42 | Pending | 2002 |
| OECD 0974533 | ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT / ORGANISATION DE COOPÉRATION ET DE DÉVELOPPEMENT ÉCONOMIQUES | 1 Chemicals2 Paints3 Cosmetics+42 | Pending | 2002 |
| OECD 0973196 · design | ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT / ORGANISATION DE COOPÉRATION ET DE DÉVELOPPEMENT ÉCONOMIQUES | 1 Chemicals2 Paints3 Cosmetics+42 | Pending | 2013 |
| OECD 0973040 · design | ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT / ORGANISATION DE COOPÉRATION ET DE DÉVELOPPEMENT ÉCONOMIQUES | 1 Chemicals2 Paints3 Cosmetics+42 | Pending | 2011 |
| OECD 0972360 · design | ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT / ORGANISATION DE COOPÉRATION ET DE DÉVELOPPEMENT ÉCONOMIQUES | 1 Chemicals2 Paints3 Cosmetics+42 | Pending | 2008 |
| OCAD 0920576 | Ontario College of Art & Design University | 1 Chemicals2 Paints3 Cosmetics+42 | Pending | 2011 |
| OSD 0904027 | BANK OF CANADA | 1 Chemicals2 Paints3 Cosmetics+42 | Pending | 1990 |
| OKKTO 2245304 · TMA1264405 | CANDEREL MANAGEMENT INC. | 35 Advertising36 Finance37 Construction+4 | Registered | 2024 |
| OESD 2192972 · TMA1219386 | Oklahoma Embroidery Supply & Design, LLC | 8 Hand9 Electronics23 Yarns+3 | Registered | 2024 |
| OST 2191468 · TMA1241210 · design | an individual | 5 Pharmaceuticals10 Medical44 Medical | Registered | 2024 |
| OGYTUHI 2183365 · TMA1231297 | Dongguan Youjia Trading Co. Ltd. | 22 Ropes | Registered | 2024 |
| OKTA 2154759 · TMA1191118 · design | YIWU MUGUO BAGS CO. LTD. | 18 Leather | Registered | 2023 |
| OUSIDE 2150242 · TMA1217303 | Shenzhen OuSiDe Technology Co. Ltd | 9 Electronics11 Lighting | Registered | 2024 |
| Oashot 2149229 · TMA1203145 | an individual | 28 Toys | Registered | 2023 |
| OYESAUTO 2134907 · TMA1214189 | Shenzhen Oyes Technology Co. Ltd | 21 Housewares | Registered | 2023 |
| OKAYD 2118203 · TMA1162743 | Proof Label Services LLC | 35 Advertising42 Science45 Legal | Registered | 2023 |
| OZAWADE 2113139 · TMA1160529 | BIOPROJET EUROPE LIMITED | 5 Pharmaceuticals | Registered | 2023 |
| OCTO 2100398 · TMA1171458 | an individual | 9 Electronics36 Finance38 Telecommunications+3 | Registered | 2023 |
| OKEDI 2089277 · TMA1211771 | an individual | 5 Pharmaceuticals | Registered | 2023 |
| OKDO 1945871 · TMA1221798 | OKDO TECHNOLOGY LIMITED | 9 Electronics16 Paper25 Clothing+5 | Registered | 2024 |
| OKDO 1923439 · TMA1221797 · design | OKDO TECHNOLOGY LIMITED | 9 Electronics16 Paper25 Clothing+5 | Registered | 2024 |