orangutan
if birds count
owl
ostrich
Mammals that start with the letter o:ocelot,old English sheepdog,opossum,orca,otter,
oscar
Oreo
Oakley
Ocean Perch and Oregon Chub are fish. They begin with the letter O.
oakland,raiders...
James Oglethorpe was the founder of the colony of Georgia. His name begins with the letter O.
Oldsmobile and Opel are the only car manufacturers I can name that start with O.
Humans, for a start.
None start with "O". Oslo is the capital of the Scandinavian country Norway.
Some words that start with the letter O are:oceanOddOdeofoffOfficeogreoldOliveOnoneOpalOppositeorOrangeorboreganoorganismorgasmorigamiotherotteroughtOxymoronoval
Barrack H. Obama is the current U.S. president. He is the only U.S. president with a name that starts with the letter O.