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...
Oldsmobile and Opel are the only car manufacturers I can name that start with O.
James Oglethorpe was the founder of the colony of Georgia. His name begins with the letter 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.