| O'Hara's Celtic Stout | Carlow Brewing Company | American Stout | 4.3% |
| O'Hara's Irish Pale Ale | Carlow Brewing Company | American Pale Ale | 5.2% |
| O'Hara's Irish Red | Carlow Brewing Company | Irish Red Ale | 4.3% |
| O'Hara's Irish Stout | Carlow Brewing Company | Irish Dry Stout | 4.3% |
| O'Hara's Leann Folláin | Carlow Brewing Company | Irish Dry Stout | 6.0% |
| O'Hara's Leann Folláin | O'Hara's Brewery | | 6.0% |
| O'Malley's IPA | Weston Brewing Company | American IPA | 7.5% |
| O'Malley's Irish Cream Ale | Weston Brewing Company | Cream Ale | |
| O'Malley's Stout | Weston Brewing Company | American Stout | 5.5% |
| O'SOO Oyster Stout | Benford Brewing | Oatmeal Stout | |
| O'sullivan Érable-Bourbon 2018 | Microbrasserie Le Prospecteur | Scotch Ale / Wee Heavy | 9.5% |
| O'zapft Is! | Garage Project | Märzen | 6.0% |
| O'Zapft'is | Fonta Flora | American Strong Ale | 9.0% |
| O-G Hazy | BrewDog Ltd | New England IPA | 7.2% |
| O-gii | Milwaukee Brewing Company | | |