| Ollopa Dekoorc Eert | Dark Horse Brewing Co. | | |
| Olly Oud Bruin | Free Will Brewing Company | Flanders Oud Bruin | 7.9% |
| Oloroso | Amalgam | Wild Ale | 5.8% |
| Oloroso Cask | Innis & Gunn | English Strong Ale | 7.4% |
| Olympe | Broadway Pub | Saison | 3.5% |
| Olympus | Night Shift Brewing | Flanders Oud Bruin | 8.4% |
| Ol’ Keeper | Microbrasserie Le Castor | Old Ale | 9.8% |
| Ol’ Lifewine BBA Barleywine Ale | Matchless | English Barleywine | 14.5% |
| Oma | Shared | Helles | 4.2% |
| Oma Lodewijk | Brouwerij Eleven | Belgian Blonde Ale | 5.5% |
| Omega | Alvinne Picobrouwerij | Wild Ale | 6.0% |
| Omega | Brouwerij Alvinne | Lambic | 6.0% |
| Omega Midnight | Ale Syndicate Brewers | Foreign / Export Stout | 9.5% |
| Omega Point | Olde Hickory Brewery | American Barleywine | 10.0% |
| Omega Point 25th Anniversary | Olde Hickory Brewery | English Barleywine | 11.7% |