Politics and Business magazines
- Osaka Gas Company, Ltd.
- Oscar Mayer Foods Corp.
- Oshkosh Truck Corporation
- Oshman’s Sporting Goods, Inc.
- OSI Restaurant Partners, Inc.
- Osmonics, Inc.
- Osram GmbH
- ÖSterreichische Bundesbahnen GmBH
- österreichische Post- und Telegraphenverwaltung
- Otari Inc.
- Otis Spunkmeyer, Inc.
- Otor S.A.
- OTR Express, Inc.
- Ottakar's plc
- Ottaway Newspapers, Inc.
- Otter Tail Power Company
- Otto Versand (GmbH & Co.)
- Outdoor Research, Incorporated
- Outdoor Systems, Inc.
- Outlook Group Corporation