O
- Offenhauser – Fred Offenhauser
- Office Kitano – Takeshi Kitano
- Öhlins – Kenth Öhlins
- Oldsmobile – Ransom E. Olds
- Olin Corporation – Franklin W. Olin
- Olivetti – Camillo Olivetti
- Orton Ceramic Foundation – Edward Orton, Jr.
- Osella – Enzo Osella
- Otis Elevator Company – Elisha Otis
- Otto GmbH – Michael Otto
Read more about this topic: List Of Companies Named After People