Onion
Opra
* Orange
As of this date (Feb. 10, 2014) there are 5 LDS Temples that start with the letter 'O'.Oakland, California, U.S.A.Oaxaca, MexicoOdgen, Utah, U.S.A.Oklahoma City, Oklahoma, U.S.A.Oquirrh Mountain, Utah, U.S.A.
Otto Van Bismarck
Some names beginning with the letter O are:OlafOleanderOliveOliverOllieOmarOpalOpheliaOprahOrvilleOscarOtto
Onimokpoy
Orlaith, Olive, Oliviea
old McDonald
Ox or oxen
Oldsmobile and Opel are the only car manufacturers I can name that start with O.
Odintsovo is a city southwest of Moscow, Russia.