| Name
| Description
| 1st App in Aquaman
|
| O
|
| O'Dowd
| A member of Lansing's gang.
| Adventure #185 (1953)
|
| Ocean Square
| A place in a seaside town in which a statue of Aquaman is placed.
| Adventure #211 (1955)
|
| Oceanographic Society
| A group that gets Aquaman to help them chart the seabed.
| Adventure #253 (1958)
|
| Octi
| Aquaman's nickname for an octopus friend.
| Adventure #103 (1946)
|
| Octy [1]
| The octopus from the aquarium who was taken care of by Old Pete after the aquarium closed.
| More Fun #101 (1945)
|
| Octy [2]
| An octopus who plugs up holes in a ship while the crew make repairs.
| More Fun #105 (1945)
|
| Octy [3]
| An octopus who assists Aquaman by helping rescuing a millionaire and his crew.
| Adventure #120 (1947)
|
| Old Hard Shell
| A giant sea turtle friend of Aquaman's.
| Adventure #134 (1948)
|
| Old Pete
| Faithful guard at the old aquarium determined to keep the larger fish that couldn't be transferred to the zoo alive.
| More Fun #101 (1945)
|
| Orienta Express
| The company offering a contract to the first ship that can reach Singapore from Hong Kong of the S.S.Cathay and the S.S.Marlin.
| Adventure #168 (1951)
|
| Orwell
| The owner of a tropical fish store that raises tropical fish in an inland lake.
| Adventure #212 (1955)
|
| Oswald
| A man having a birthday party aboard a ship on which all the musicians got seasick. Topo filled in for them.
| Adventure #266 (1959)
|
