Nazi Germany eventually won a prolonged World War II due to a Japanese invasion of California and the development of nuclear weapons by the Nazis.
In this reality, Nazi Germany won World War II due to the Kryptonian known as Overman having landed in 1938 and raised by Adolf Hitler. Earth became an oppressed world under Nazi rule as hundreds of thousands of facilities are used for separating genetic lines, in which those deemed inferior are killed and others will be used to breed. Resistance against the current regime are the Freedom Fighters.
Many of the superhumans on Earth owe their powers to the "metagene", a genetic feature of unknown origin, which causes some people to develop superpowers when exposed to dangerous substances and forces. Others owe their powers to magic, genetic manipulation (or mutation) or bionics (see below). A large power gap resides between most superheroes and civilians. Still others owe their powers to not being human at all (see races, below). There are also superheroes and supervillains who possess no superhuman powers at all but rival their effectiveness with specialized equipment or "to the absolute limit of human potential" training in special skills, such as martial arts.
The American government has had a more wary approach, however. Back during the War they started "Project M" to create experimental soldiers to fight in the war, such as the Creature Commandos.
There are a few intelligent races living on Earth that the public at large did not know about until recent times.
the last survivors of Atlantis, who changed themselves into water-breathing forms, including the human-like Poseidonians and the mermaid-like Tritonians.
a tribe of highly intelligent, telepathic gorillas living in an invisible city hidden in Africa; this is the home of Gorilla Grodd.
There are many intelligent extraterrestrial races as well. Curiously, a large number of them are humanoid, even human-like, in form (such as Kryptonians, who outwardly appear identical to Earth-born humans); some can even interbreed with Terrans. Some of these races have natural superpowers, but they're usually the same for all individuals of the same race, unlike Earth's metahumans. This was explained by the fact that in Earth's distant past Martians experimented on humanity, severely culling the metahuman potential; this means that a species that was meant to have a wide range of powers, like Tamaranians or Kryptonians, ended up "just...human". However, there are also plenty of non-humanoid races as well.
The DC Universe has had many natural and cosmic disasters happen to their alien civilizations. The Martians were destroyed by war, the Kryptonians by a dying planet, and the Czarnians by plague. Even the Almeracian Empire was victim to impending destruction by Imperiex.
There are several lesser beings in the DC universe that possess god-like powers, through energy manipulation, magic ability, or technological advancement. Magic and the supernatural are often depicted as being real in the DC Universe, though some skeptics such as Mister Terrific maintain that there are scientific explanations to all such events. Magic is too powerful in the physical world, where harnessing magic can distort and even destroy reality if not properly controlled (i.e.: if the Lord of Order succumbs to certain events so will the Lord of Chaos).
The first beings calling themselves 'gods' first appeared billions of years ago on another planet, but they destroyed themselves in a terrible war. This unleashed the "Godwave," a wave of cosmic energy from the Source. This gave birth to other gods across the universe, including Earth’s. From the planet’s remains were formed the worlds of Apokolips and New Genesis, inhabited by beings that call themselves "New Gods". The Source Wall is an archetype of Buddha on the edge of the known galaxy. Certain speedsters believe in enlightenment in order to become part of the Speed Force (see below). Kismet is an immortal god and the embodiment of reality. In mortal form she was member of the Lords of Order. Depending on the characters, other diverse religious deities from ancient cultures are common. Heroes such as Aztek and Black Condor, or villains like Black Adam, have found knowledge of their native roots in origin.
The Lords of Order and Chaos
These two groups of magical beings have been fighting against each other since the beginning of time, and they often empower others (with "Order Magic" or "Chaos Magic") in exchange for their acting as their agents. Many magical heroes and villains have been manipulated by them.
The Earth itself has a living spirit called "Maya" who, for millennia, has been creating champions, one for each of the mystical elements, to protect itself, using human beings as their hosts. Swamp Thing, Firestorm, Naiad and Red Tornado were some of them.
a subspecies of humanity with the natural ability to use magic, this race almost disappeared after too much crossbreeding with normal humans (it's from them that people in the DC universe inherited the ability to use magic.) The last pure blooded ones decided to retire to a magical invisible city centuries ago, and are now known as "The Hidden Ones". Zatanna knows many of the race's secrets, and Traci Thirteen is currently investigating magical and occult phenomena for the Croatoan Society—both women had Homo Magi mothers.
Like the Endless, these beings were created from the emotional energy generated by sentient beings. Each of the seven emotional manifestations of the DCU is represented by a different color (rage, red; greed, orange; fear, yellow; will, green; hope, blue; compassion, indigo; love, violet) and being. The various power-ring based corps of the DCU, most notably the Green Lantern Corps and Sinestro Corps utilize the energies of these beings.
Wizards and Sorcerers
Various sorcerers lurk in the DCU. Dr. Fate, Circe, the wizard Shazam, Mordru and Felix Faust are written as characters who use sorcery to create and destroy. Dimensions, rituals and spiritual realms are sources for magic power as seen in Ras Al Ghul's Lazarus Pit, Doctor Occult's use of the astral plane and the transformations of Captain Marvel.
Demonic entities vary from the Demon Etrigan, to Blaze, Satanus and Neron. Demonic entities are abundant and come from Hell although some like Eclipso, the vengeance demon (also referred to as the Prince of Darkness), reside on the Moon. Demonic Entities from Wonder Woman comics are directly linked to Greek Mythology such as Hades, and Ares. In the Vertigo comics, characters like John Constantine oppose demons influenced by Christian mythology. Most Demons are not however directly linked to Demonology.
The V League
The Axis Justice League
Technology more advanced than that which normally exists is available - but it is usually very expensive, and usually only rich or powerful individuals and organizations (or the scientific geniuses who create them) have access to them. S.T.E.R.N Labs is a Nazi research outfit that often develops these devices.. It must also be noted that the government also runs the secret Project Agoge (located in the Alps) to develop clones and genetic manipulation without the public's knowledge. Technology can also come from outer space or different time-lines.
Robots and similar creations, including cyborgs, can have superior intelligence when they are created as sentient beings. The Manhunters, the Metal Men, Red Tornado, Robotman, Hourman, and Metallo are but a few examples. These 'beings' are most often created by individuals who possess vast intellects, like scientists Professor T.O. Morrow (maker of the Red Tornado), Dr. Will Magnus (who constructed the Metal Men) and Professor Ivo (who fabricated Amazo and other advanced androids using a form of Nano-technology developed by Lexcorp). Brainiac also emulates this technology as well as technology from other worlds. Similarly, some characters use technology to enhance their armor or modify cybernetic functions, for example Steel, and Cyborg .
DC Database Earth 10 Article- http://dc.wikia.com/wiki/Earth-10
DC Database Prime Earth Article- http://dc.wikia.com/wiki/Prime_Earth
Wikipedia DC Universe Article- http://en.wikipedia.org/wiki/DC_Universe