| 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% |
| O.K. Beer | Browar Okocim | | |
| O.N.E. (Our Nastiest Effort) | De Struise Brouwers | Belgian Dark Strong Ale | 10.0% |
| O.P. (Sole Composition Series) | Upright Brewing Company | American Stout | |
| O.P.W. | Fiddlehead Brewing | American Pale Wheat Beer | 5.5% |