| Onward Stout | Yazoo Brewing | American Stout | 3.8% |
| Ook Best Lekker! | Brouwerij De Molen | Wild Ale | 6.5% |
| Oompa Loompa | Fat Head's Brewery & Saloon | American Stout | 6.5% |
| Oompa Loompa Chocolate Stout | Rocky River Brewing | | |
| Oort | Ecliptic Brewing Company | American Imperial Stout | 8.5% |
| Oosik Amber Ale | Midnight Sun Brewing Co. | American Amber / Red Ale | 5.0% |
| Op & Top | Brouwerij De Molen | English IPA | 4.5% |
| Opal | Cigar City Brewing | | |
| Opal | Firestone Walker Brewing Co. | Saison | 7.5% |
| Open Container | Midnight Sun Brewing Co. | Wild Ale | 6.0% |
| Open Season | Rainwater Brewing | | |
| Operis | Four Winds Brewing | Saison | 7.0% |
| Opperman's Bourbon Barrel Aged Plead The 5th | Dark Horse Brewing Co. | American Imperial Stout | 11.0% |
| Oppermann's Barrel-Aged Neapolitan Milk Stout | Saugatuck Brewing Company | Sweet / Milk Stout | 6.5% |
| Optimal Wit | Port City Brewing Company | | 4.9% |