Dark Age Europe

A time of anarchy and chaos (roughly 400-~1066 AD) when most people were disease-ridden and covered with filth, unless they happened to be kings. The cleanest and most well-known king of this time was King Arthur, the King(-ish) of the Britons who had a round table around which sat his band of noble and chivalrous ~~knights~~ guys with weapons (many of whom proved to be not so noble and chivalrous when left to their own devices). Since most popular culture portrayals of him were written centuries after he lived (featuring fashion and architecture from those eras), many Hollywood Historians choose to lump him in with The High Middle Ages (but hey, when have they ever been sticklers for accuracy?).

This period heralded the fall and splitting of Rome, and the rise of Monasticism in Europe. Most Hollywood monks are pious men clad in long brown robes, with rosaries and tonsure haircuts. They frequently spend all their day dipping feathered pens into inkwells and scribbling strange script into large books by candlelight. (This, when they're not out chasing lusty, busty tavern wenches. Hollywood Monks don't tend to take that whole "celibacy" thing all that seriously, though historically celibacy was not a standard part of the clerical life until later in the Middle Ages. Some clerics even considered prostitution to be a necessary evil. It was, however, mandated in nearly every set of monastic rules, including those of Benedict.)

But it is also a time of interesting contrasts, during this period Christian and Pagan beliefs and their traditions were syncretized, which gave origin to some of the most famous mythologies and legends of the middle ages, like Beowulf, Siegfried and the aforementioned King Arthur among many others.

The term "Dark Ages" only really makes sense if you know the technical definition of the word "history", which is, "The study of the things people wrote about themselves back in the day." As such, the Dark Ages are dark not because it was Darker and Edgier and there was very little lighting but because very little was written at the time, leaving History in the dark (ha-ha) about what things were like. The other reason historians view the time as 'dark' is that of those writings that were produced, few survive to the modern day. We cannot tell you definitively that The Dark Ages were more dark and edgy than the eras that came before and after; in fact, depending on your perspective, in some places the lack of Roman overlords breathing down your neck could be seen as an improvement. In fact, there are plenty of reasons to suppose the Early Medieval era was vastly superior to antiquity in terms of quality-of-life. Due to the misleading nature of the name, and that modern archaeology and research has uncovered more information about this period than its coiners had access to, modern historians tend to eschew the term "Dark Age(s)" in favor of terms like "Early Middle Ages" or "Early Medieval".

Public Domain Characters & Public Domain Artifacts of this era:

King Arthur
- Excalibur, his sword
  - Excalibur in the Stone, the confusion of Excalibur and the original Sword in the Stone.

Related Useful Notes pages:

The Low Middle Ages: Is there really a difference?
Norse Mythology
Celtic Mythology
Slavic Mythology: Provided you can find a piece of media involving it, heh heh.

Popular tropes for works set in this time period are:

An Axe to Grind: Axes were probably the most frequent non-spear weapon of the era, as an axe is fairly easy for a relatively unskilled smith to make, and peasants tended to have these around anyway for firewood (though battle axes generally differed from wood axes).
Ancestral Weapon: Often Truth in Television, as the difficulties of making steel and pattern welding made high-quality blades expensive,not to mention the shortage of metals, and they tended to get passed down, some eventually receiving a name and a legendary Backstory.
Barbarian Hero
Blade on a Stick: What most fighters actually had to settle for, when they weren't stuck with farming implements or just the stick.
Carry a Big Stick
Droit du seigneur
Drop the Hammer
The Dung Ages
Feudal Overlord
Here There Were Dragons
Heroic Fantasy
Horny Vikings
The Time of Myths: Can overlap, depending on the degree of realism.
Vestigial Empire: The Roman Empire was alive and (relatively) well in the east. It maintained its infrastructure, literate culture, and a higher standard of living, but its territory was reduced considerably.

Works set in this time period include:

Film

All movie and literary versions of King Arthur.
Monty Python and the Holy Grail. The Pythons admit that Anachronism Stew is at work: It is said to be set in Dark Ages Britain, but the costumes are based on fashions from the 1300s.
The 13th Warrior
Beowulf and Grendel (2005)
Beowulf (2007)
Outlander (2008), i.e., Beowulf, the Sci-Fi Remix.