| Old Oak Amber Ale | Carver Brewing Co. | American Amber / Red Ale | |
| Old Odense Ale | Nørrebro Bryghus | Herb and Spice Beer | 7.5% |
| The Old Order I | Solemn Oath | Saison | 10.0% |
| The Old Order II | Solemn Oath | Saison | 10.0% |
| Old Peculier | T&R; Theakston | | 5.7% |
| Old Perseverance | Avery Brewing Company | Old Ale | 18.5% |
| Old Plowshare | North Coast Brewing Co. | American Stout | 5.7% |
| Old Port Porter | Port Washington Brewing | American Porter | |
| Old Potentate | Southern Star Brewing Company | Old Ale | 7.2% |
| Old Powderhouse | Mystic Brewery | | |
| Old Powerhouse Lager (discontinued) | Gottberg Brew Pub | American Lager | |
| Old Princeton Landing IPA | Half Moon Bay Brewing | American IPA | 6.1% |
| Old Pro Gose | Union Craft Brewing | Gose | 4.2% |
| Old Prospector | Auburn Alehouse | English Barleywine | 10.0% |
| Old Rasputin Russian Imperial Stout | North Coast Brewing Co. | Russian Imperial Stout | 9.0% |