Octopi-men: 1940, Science Comics #5 (Fox). The violent Octopi-men reside in a hidden grotto where a sunken Roman galley lies. Unfortunately for them, Captain Nemo is looking for the galley and is joined by Navy Jones and Princess Coral. When the trio are trapped in the grotto, the octopi-men attack them but ultimately repulsed, thanks to the timely intervention of the Nautilus and her crew.
Octopus: Wonderworld Comics #30 (Fox). A true misfit with 3 arms and an apish fanged face, this man devoted himself to becoming the number one gang-leader. A mirrored invention that would fire an aimed electrically charged blast when it caught a ray of light allowed him to weak havoc against his rivals. The beam almost spelled an end to the hero called the Flame, causing him to reveal his identity and source of powers to his girlfriend Linda so that she might carry on as Flame Girl. However, the Flame does not die and the two heroes battle the Octopus and his gang. The Octopus is set aflame during the battle and he flees into the garage which then blows to kingdom come.
Octopus II: Target Comics. Bald master criminal that was decked out in a mask and a shirt (robe?) with an octopus on the cover. Fought the T-Men (agents of the Treasury Dept).
Hans Odin: X-Venture.Commander of a Prisoner of War Camp and when Germany loses the war, he flees to Africa to evade not only justice but the wrath of Jack Tamor whose brother died in his camp. Though he manages to become a councilor in the native tribe Bar-Ongi, Tambor manages to catch up to him, and after a brief enslavement, free the white slaves and exact his justice. Tamor, disgusted with civilization, opts to stay in the jungles. Beautiful blonde Ayilia, leader of the slaves goes with him. NOTE: As fairly common with strips of this type though this is the African Congo, the native tribe looks more South American and of course a pretty white woman is also on hand. Ayiila says the slaves are her people but where they come from and their own future is uncertain.
Og, King of the Ape-Men: (Fox). In the Malay jungle, Dr. Fung and Dan Barrister are searching for the daughter of the Earl of Winlliston lost years before and hear of the rumors of a white woman living with Ape-men.
Ohisis: 1943, Four Favorites #9 (Ace). 4,000 years ago in ancient Egypt, Princess Ohisis, daughter of pharaoh Ibis (sure there's no relation) and beloved of Fadouah lived. Fadouah was an alchemist and he discovered the secret of immortality and had Ohisis drink it. Before he can also partake of the potion, the Nile overflows and he rushes to save his countrymen only to be mortally wounded by a falling column. Ohisis doesn't want immortality without him and so he tells her that the antidote is in some imitation diamonds, crushing them will make a powder that she can swallow and die. Alas, the flood had destroyed his laboratory and washed away the diamonds, losing them somewhere buried in the mud. Ohisis lives a long life, watching civilizations come and go until the diamonds are discovered in the modern day. This brings her into conflict with the criminal the Clown who in an attempt to steal some government diamonds instead gets the imitation Egyptian ones while she accidentally makes off with the real ones. They work out a deal while Magno & Davey are caught in the middle. True to form, the Clown double-crosses her and she delivers what should be mortal wounds to him. Then she crushes the fake diamonds and joins her beloved Fadouah in death.
Old Man of the Mountain: 1941, Pocket Comics #2 (Harvey). In a crater of an extinct volcano in the Andean mountains, the Old Man of the Mountain is a mad scientist. He kills all that come across him and so his crater is a mass graveyard of lost pilots. He dies trying to kill Spin Hawkins, falling into a pit.
The One: 1940, Exciting Comics #1 (Better). In Midtown, two gangs of racketeers are working the town over to the point that Mayor Kurt Piersole enlists the aid of freelance gangbuster Gunner Thompson and points him in the direction of the DA as possibly being the "One", leader of one or both groups. Gunner uncovers the fact that it's none other than Mayor Piersole himself.
One Thousand and One: 1940, Keen Detective Funnies #19 (Centaur). It's a vast criminal organization headed by three hooded men and foes of G-man "TNT" Todd (before he became a superhero). Captured with the timely aid of a mystery man calling himself Mr. Death in issue #20.
One-Eye: 1940, Fantastic Comics #13 (Fox). Missing his left eye has left One-Eye bitter, and he has his base under the sea with strange humanoid beings as well as monsters such as a giant devil octopus. He starts poisoning the seas, fumes overwhelming ships. He's captured by Sub Saunders.
Oo-Lhat: 1939, Champion Comics #2 (Harvey). In ancient Egypt, Oo-Lhat was a high priest of Osiris. However, he let greed for gold and power and lust for the princess to overcome his priestly duties and he murdered a man. Fleeing justice, he found the worshippers of the Blazing Scarab, a glowing scarab suspended over the black altar of Set. He discovers the scarab is a key between a timeless dimension and this one. There with the scarab worshippers, he establishes an almost immortal city called Baracs. They formed a link to the outside world at the oasis of Memthet where they would lure and kill travellers through their League of Assassins. They aged only during their raids of caravans and their immortality was linked to reason and thought, thus beasts of burden could not come through the portals. Even if a man's brain and heart were destroyed, he still remained, just losing his identity and part of his visibility. Eventually, the Oasis was buried in a sand-storm.
However, the discovery of the scarab and activating it by Walt Worthington in the present day, allows Oo-Lhat to renew his designs of conquest and pillaging, leaving Walt and his servant behind with the women. When Walt convinces the women to accompany him to this world, it is sadly discovered, that once here, their true ages catch up with them after so much time and Walt and his servant are left alone in a field of skeletons.
Orchid: The beautiful sister and aide of the Dragon. Foe of Samson.
Orchid Princess: 1944, Mystery Comics #2 (Better). She opposed attempts by the jungle boy Zudo, Dr. Turner, and Dr. Howard in finding the rare Black Orchid.
Ornitz: A spy for a gang of saboteurs eavesdrops on Doctor Clark when he and Dick Martin (aka Pyroman) discover some ancient bacteria that live in iron ore, converting the metal into sustenance. However, the spy thinks it's the secret of Pyroman's abilities and gangmember Ornitz is injected with the stuff. Instead, his body becomes like steel itself making him an equal to Pyroman. Not only that, he somehow reasons that injecting samples from his own blood will make others like him only under his control and he does so by holding false inoculations for a troop of soldiers.. He dies while fighting Pyroman, he falls on a sharp rusted piece of metal, rust being the one thing that kills the bacteria (luckily, instantly). The death of the leader also cancels out the powers and hypnotic hold over the others.
Owens, William: 1941, Thrilling #14 (Standard). In 1914, scientist William Owens discovered Wonderol, a powerful tonic. Unfortunately, his financiers stole the rights to it from him and he swore revenge. Flash forward a couple of decades and some change, and he starts making good on that threat, killing off the company founders one by one. Owens somehow got a ruthless gang working for him and he possessed some new discoveries including a powerful gas, a huge glass encased gas bomb, and even a paralyzing bullet, from which even a scratch can lay the mighty low. His defeat comes when Doc Strange and Virginia investigate the series of murders. He is killed when he is thrown into his gas bomb, breaking the glass shell.
Owl-Eyes: Crackajack Funnies (K.K. Publications). A smuggler with his own submarine (albeit a little rundown) and crew that faced off against Don Winslow. The bald-headed fiend was so nick-named due to his wide-awake bulging eyes.