| 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 | | |
| O-H! | Triple Digit Brewing Co | | |
| O-Tay Bockwheat | Egan Brewing | | |
| O.B. Vanilla Rye | Honey Pot Meadery | | |
| O.B.B | Honey Pot Meadery | | 15.0% |
| O.D.B. | Sawdust City Brewing Company | Saison | 10.0% |
| O.F.D. | Dorchester Brewing Company | Imperial IPA | 8.3% |
| O.G. 1111 Rifermentata | Birra del Carrobiolo | English Barleywine | 13.0% |