| HYDRIL 0326457 · TMA184668 | HYDRIL COMPANY (A DELAWARE CORPORATION) | 1 Chemicals2 Paints3 Cosmetics+10 | Registered | 1972 |
| HYDRIL 0148329 · TMDA47640 · design | HYDRIL COMPANY (A DELAWARE CORPORATION) | 6 Metal7 Machines8 Hand+1 | Registered | 1929 |
| HYDROLIQ 2136716 · TMA1236974 | an individual | 1 Chemicals5 Pharmaceuticals37 Construction+1 | Registered | 2024 |
| HYDRAL 1693589 · TMA923995 | Huber Specialty Hydrates, LLC | 1 Chemicals | Registered | 2015 |
| HYTROL 0371389 · TMA208280 | HYTROL CONVEYOR COMPANY, INC. | 7 Machines | Registered | 1975 |
| HYDRAUL 0339482 · TMA180447 | IMPERIAL OIL LIMITED | 4 Oils | Registered | 1971 |
| HYADROL 2108978 | an individual | 5 Pharmaceuticals10 Medical | Pending | 2021 |
| HYDROLINK 1811547 · TMA1003988 | Trojan Battery Company, LLC, a Delaware limited liability company | 9 Electronics | Registered | 2018 |
| HYDROLINK 1754107 · TMA984987 | WaterFurnace International, Inc. (Corporation Indiana) | 9 Electronics | Registered | 2017 |
| HYDROLINK 1631777 · TMA1027115 | Toray Kabushiki Kaisha (Toray Industries Inc.) | 10 Medical | Registered | 2019 |
| HYDROLITE 1454527 · TMA847582 | an individual | 1 Chemicals3 Cosmetics | Registered | 2013 |
| HYDROLICO 2347003 · design | Bailey International, LLC | 7 Machines9 Electronics35 Advertising+1 | Pending | 2024 |
| Hydrolite 2282594 | an individual | 21 Housewares | Pending | 2023 |
| HYDROLUX 2059809 · TMA1239404 · design | 9399-7070 Québec inc. | 1 Chemicals | Registered | 2024 |
| HYDROLUX 1346459 · TMA770779 | ChemSpec USA, LLC | 1 Chemicals2 Paints | Registered | 2010 |
| HYDROLAC 1336816 · TMA717451 | Sally Beauty International, Inc. | 3 Cosmetics | Registered | 2008 |
| HYDROLUX 0434935 · TMA240589 | Kohler Canada Co./Compagnie Kohler Canada | 11 Lighting | Registered | 1980 |
| HYDROLOK 0339190 · TMA182557 | Hydro-Aire Aerospace Corp. | 6 Metal8 Hand20 Furniture | Registered | 1972 |
| HYDROLOGIC 1784097 · TMA993162 | WaterFurnace International, Inc. an Indiana corporation | 7 Machines11 Lighting | Registered | 2018 |
| Hydrolysis 2279275 | an individual | 36 Finance45 Legal | Pending | 2023 |
| HYTREL 0346309 · TMA185231 | DuPont Polymers, Inc. | 1 Chemicals17 Rubber | Registered | 1972 |
| Hydroleaf 2224807 · TMA1251185 | Hydroleaf Intelligent Produce Co. Ltd. | 29 Meat30 Coffee31 Fresh+1 | Registered | 2024 |
| Hydryalix 2031057 · TMA1148931 · design | Allergan Pharmaceuticals International Limited | 5 Pharmaceuticals | Registered | 2022 |
| HYDRAULEX 1905412 · TMA1105525 · design | Attica Hydraulic Exchange, Inc. | 7 Machines35 Advertising37 Construction | Registered | 2021 |
| HYDRAULEX 1905411 · TMA1105524 | Attica Hydraulic Exchange, Inc. | 7 Machines35 Advertising37 Construction | Registered | 2021 |