Well well, English History of the Early Dark Ages is perhaps understandably not everybody's strong point. No matter!
In fact it was 1600 years ago (a round number at last!) that the Dark Ages (in England at least) started, when an appeal to Rome for help was rejected. In 410 AD, you see, the Western Roman Empire was being over-run by Vandals, Goths, Visigoths, Huns, Ostrogoths, Saxons, Jutes, Germanii, Franks, Alemanii, and general riff-raff from Northern Europe and Western Asia. This led, anyway, to the Roman withdrawal from Britannia. The Picts of Scotland and Scots of Ireland (don't ask...) took the opportunity to invade and so began, it seems, a long period of fighting across the whole of Britannia.
Now the reason this period is called the Dark Ages is because we don't know much of what went on, and what we do know is probably in part myth. (In fact, the legend of King Arthur starts in histories written about this time - if there was such a person then he wasn't a knight but a warrior.)
What is true, or very likely to be true, is that outof this period one Briton took a central role in the defence of Britannia. That person was Vortigern - which isn't actually a name but a title meaning "overlord". Again so little is known about him but most histories tend to agree that Vortigern, in seeking to protect England from the Pict and Scot invaders, asked the Saxons under Hengist and Horsa to come to Britain and fight for Vortigern. This didn't exactly go to plan, and eventually the Saxons too became an invading army.
The dust settles somewhat by about 600AD, when the four Kingdoms of Wessex, Mercia, Northumberland and East Anglia are established as the main Saxon Kingdoms in Britain. Curiously, despite the fact that the main invading force was Saxon, the new country would become known as England, from the lesser tribe of the Angles.
So anyway, my person-of-the-article is Vortigern, the man who made England.