| HYDROIL 0327863 · TMA176091 | Dodge Industrial, Inc. | 7 Machines11 Lighting | Registered | 1971 |
| HydroTrim 2206088 · TMA1231871 | an individual | 5 Pharmaceuticals | Registered | 2024 |
| Hydrogrid 1831521 · TMA1056739 | HYDROGRID GmbH | 36 Finance42 Science | Registered | 2019 |
| HYDROTRIM 1482292 · TMA806346 | CertainTeed Gypsum and Ceiling Manufacturing, Inc. | 17 Rubber | Registered | 2011 |
| HYDROFILL 1446800 · TMA828648 | MICROVENTION, INC. (a Delaware corporation) | 10 Medical | Registered | 2012 |
| HYDROFOIL 1442795 · TMA828875 | MEC MOUNTAIN EQUIPMENT COMPANY LTD. | 25 Clothing | Registered | 2012 |
| HYDROBOIL 0613175 · TMA387921 | ZIP HEATERS (AUSTRALIA) PTY LIMITED | 11 Lighting | Registered | 1991 |
| HYDROLIQ 2136716 · TMA1236974 | an individual | 1 Chemicals5 Pharmaceuticals37 Construction+1 | Registered | 2024 |
| HYDROSOL 1936343 · TMA1160811 | Hydrosol GmbH & Co. KG | 1 Chemicals29 Meat30 Coffee | Registered | 2023 |
| HYDROPEL 1917541 · TMA1101869 | an individual | 19 Building | Registered | 2021 |
| HYDROMIX 1795407 · TMA988578 | Hayward Gordon ULC | 37 Construction40 Treatment42 Science | Registered | 2018 |
| HYDROMIX 1750449 · TMA1007578 · design | an individual | 7 Machines37 Construction | Registered | 2018 |
| HYDROKIT 1575635 · TMA902594 | Danco, Inc. | 11 Lighting | Registered | 2015 |
| HYDROFIT 1549497 · TMA887098 | OTIS ELEVATOR COMPANY | 7 Machines9 Electronics37 Construction | Registered | 2014 |
| HYDROCEL 1472489 · TMA795061 | American Air Filter Company, Inc. | 7 Machines | Registered | 2011 |
| HYDROFIX 1414436 · TMA764491 | Danco, Inc. | 11 Lighting | Registered | 2010 |
| HYDROSAL 1239410 · TMA685262 | Bausch Health, Canada Inc. | 5 Pharmaceuticals | Registered | 2007 |
| HYDROMIX 1126602 · TMA586267 | Hydrofarm, LLC | 1 Chemicals | Registered | 2003 |
| HYDROPEL 1088412 · TMA588364 | AOC, LLC (Delaware limited liability company) | 1 Chemicals | Registered | 2003 |
| HYDROVAL 1083432 · TMA572738 | TARO PHARMACEUTICAL INDUSTRIES, LTD. | 5 Pharmaceuticals | Registered | 2002 |
| HYDROPEL 0827102 · TMA496550 | LTP SPORTS GROUP INC. | 24 Textiles | Registered | 1998 |
| HYDRONIC 0823117 · TMA486110 | Eberspächer Climate Control Systems GmbH | 11 Lighting | Registered | 1997 |
| HYDRONIX 0681060 · TMA406813 | HYDRONIX LIMITED | 9 Electronics | Registered | 1993 |
| HYDROGEL 0492632 · TMA297949 | PPG Architectural Coatings Canada, Inc./PPG Revêtements architecturaux Canada, inc. | 13 Firearms | Registered | 1984 |
| HYDROCOL 0394914 · TMA220291 | an individual | 1 Chemicals | Registered | 1977 |