| Oldest Viscosity | Port Brewing Company | American Imperial Stout | 12.0% |
| Oldmanbearma | Mortalis | Imperial IPA | 8.0% |
| The Oligarch | Breakside Brewery | American Imperial Stout | |
| Oliver / Stillwater - People Power | Stillwater Artisanal / Oliver Brewing | American Pale Ale | 6.0% |
| Oliver ESB | Wharf Rat | Extra Special / Strong Bitter (ESB) | |
| Oliver Irish Red | Wharf Rat | Irish Red Ale | |
| Oliver Pagan Porter | Wharf Rat | American Porter | |
| Oliver Twist 20th Anniversary Ale | North Coast Brewing Co. | Doppelbock | 11.6% |
| Oliver's Traditional Cider | Olivers Cider & Perry | | 6.0% |
| Olivia | Monkish Brewing Co. | Wild Ale | 6.8% |
| Olivia 9 | Claim 52 | Belgian Dark Strong Ale | 9.0% |
| Ollie Ollie Oxen Free | Perennial Artisan Ales | American IPA | 4.5% |
| 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% |