| SERIOUS 1668744 · TMA980882 | Unilever Global IP Limited | 3 Cosmetics | Registered | 2017 |
| SERIOUS: 1612194 · TMA937437 | Serious Labs Inc. | 9 Electronics16 Paper41 Education+1 | Registered | 2016 |
| SERIOUS B 1568831 · TMA861461 · design | Owner not shown | 25 Clothing | Registered | 2013 |
| SERIOUS FUN 1582603 · TMA1063473 | Serious Fun Children's Network, Inc. | 35 Advertising36 Finance41 Education | Registered | 2019 |
| GET SERIOUS 1469306 · TMA783327 | San Juan Coffee Roasting Company Ltd. | 21 Housewares25 Clothing29 Meat+3 | Registered | 2010 |
| SERIOUS FUN 1299359 · TMA775310 · design | R H Smith & Son (Wigmakers) Limited | 3 Cosmetics4 Oils6 Metal+12 | Registered | 2010 |
| SERIOUS FUN 0906159 | Cystic Fibrosis Canada | All goods and services | Protected | 1993 |
| SERIOUS SAM 2218135 | Devolver Digital, Inc. | 9 Electronics16 Paper25 Clothing+2 | Pending | 2022 |
| SERIOUS COLD 1763431 · TMA968671 | Intercontinental Great Brands LLC | 30 Coffee | Registered | 2017 |
| SERIOUS:LABS 1612193 · TMA937436 | Serious Labs Inc. | 9 Electronics16 Paper41 Education+1 | Registered | 2016 |
| SERIOUS PLAY 1458668 · TMA832375 | Owner not shown | 16 Paper35 Advertising41 Education | Registered | 2012 |
| SERIOUS MONEY 2183873 | Forstrong Global Asset Management Inc. | 9 Electronics16 Paper36 Finance+1 | Pending | 2022 |
| SERIOUS REPAIR 1674754 · TMA913876 | The Procter & Gamble Company | 3 Cosmetics | Registered | 2015 |
| SERIOUS TRUCKS 1334771 · TMA759844 | Daimler Truck North America LLC | 35 Advertising | Registered | 2010 |
| SERIOUS COFFEE 1197617 · TMA631450 | San Juan Coffee Roasting Company Ltd. | 30 Coffee35 Advertising | Registered | 2005 |
| SERIOUS GROWING 1932521 · TMA1243541 | BW GLOBAL STRUCTURES INC. | 1 Chemicals6 Metal7 Machines+10 | Registered | 2024 |
| SERIOUS SHAMPOO 1704896 · TMA983514 | Unilever Global IP Limited | 3 Cosmetics | Registered | 2017 |
| All Day Serious 2205301 | an individual | 16 Paper25 Clothing28 Toys | Pending | 2022 |
| SERIOUS BUSINESS 1793263 · TMA1036193 | an individual | 25 Clothing | Registered | 2019 |
| SOFTBALL SERIOUS 1669400 · TMA1032295 | RUSSELL BRANDS, LLC a Delaware limited liability company | 28 Toys | Registered | 2019 |
| SERIOUS SKINCARE 1612282 · TMA882899 | Flageoli Classic Limited, LLC | 3 Cosmetics | Registered | 2014 |
| NATURALLY SERIOUS 1933102 · TMA1116739 | Khani LLC | 3 Cosmetics5 Pharmaceuticals | Registered | 2021 |
| FOR SERIOUS COOKS 1528951 · TMA854374 | an individual | 8 Hand16 Paper21 Housewares+8 | Registered | 2013 |
| SERIOUS MATERIALS 1408132 · TMA799172 | SERIOUS MATERIALS, INC. | 2 Paints17 Rubber19 Building+1 | Registered | 2011 |
| SERIOUS SKIN CARE 1311263 · TMA712290 | Flageoli Classic Limited, LLC | 3 Cosmetics | Registered | 2008 |