Man... people in the past had such cool names. Alexander the Great, Pompey the Great, Cyrus the Great. Okay, there were a lot of greats. But just how does one get one of these cool monikers? Let's look at some classic Medieval English kings.
Edward the Confessor
Edward the Confessor (1003/5- 1066, reigned 1042-66) was the last Anglo-Saxon king of England. As a young man, he was the last of his siblings in line to the throne, as his name is always listed last on charters. His father was unseated in 1016 so Edward spent a quarter of his life in exile. It's suggested he was in Normandy, Northern France, for much of this time, but we can't be certain about this before c. 1030- we can place him because he witnessed four charters in the early '30s, signing two of them as the King of England (even though one of his brothers, Alfred, may have been still alive). This was quite a bold thing to do. It made certain there was a record that he was making a claim to the throne, and given father's usurper's son, Cnut the Great (there's another one) was currently the King of England, Denmark, Norway and parts of Sweden, that's not an idle remark. Cnut's territory was known as the North Sea Empire, by the way, and you should really look it up sometime. Edward's mother had also married Cnut in 1017. That probably stung a little.
Cnut remained on the throne until 1035, when he died, making Harthacnut king of Denmark. It's not certain whether he intended to bequeath his English throne to Harthacnut too, but what actually followed was a period in which Harold Harefoot, Harthacnut's elder half-brother was regent while Harthacnut was busy settling things in Denmark. Edward and Alfred both invaded at this point and the latter was captured by Godwin, Earl of Wessex, who turned him over to Harefoot. Harefoot had Alfred blinded, y'know, as any self-respecting man does to his enemies (caution: sarcasm), which is probably why Edward had Godwin exiled when he became king. Alfred died of his wounds, in case you were wondering. Edward fought a skirmish near Southampton, decided discretion was the better part of valour, and retreated back to Normandy.
In a move literally everyone was expecting, Harold Harefoot made himself King of England. Harthacnut planned to invade, but Harefoot died in 1040, meaning Harthacnut crossed the channel and made himself king without difficulty.
That should have been in for Edward, but Harthacnut was not long for this world. He invited Edward back to England, presumably as an heir in 1041, and died June 8th 1042, leaving Edward, improbably, to become king of England. There'd been three English monarchs between Edward and his father's reigns. That's probably a record.
His reign was pretty uneventful (as far as we're concerned anyway. The rise of the Godwin family is pretty interesting), but when he died in 1066, he too had no heir. Remember all that time he spent in Normandy? Well, the official claim on the part of William of Normandy (better known as William the Conqueror) was that Edward had made him heir during that time. Harold Godwinson (the same Godwin who had Alfred's eyes burned out) claimed that he, too had been made heir, and indeed Edward had been dependent on the Godwins since the 50s. A Viking king called Harald Hardrada also made a claim to the throne, based on some sort of agreement that Harthacnut had apparently had with his father, Magnus. It's pretty tenuous, anyway.
Well, surely then he should be called Edward the Indecisive! Or Edward the Blown About By Winds of Fortune? Or Edward the In The Right Place At The Right Time? What's this Confessor business all about?
Sorry, I got a little bogged down in all the cool succession crises and stuff. Edward was also, apparently, super-pious, and "Confessor" is a religious epithet reserved for those who lived holy lives without becoming martyrs. He was canonised (made a saint) in 1161.
Richard the Lionheart
Okay, that Edward guy wasn't amazing, but Richard the Lionheart was AWESOME, RIGHT? I mean, with the Crusades, and the evil brother and the Robin Hood thing. I mean- he was played by Patrick Stewart that one time! He lived 1157-1199 and ruled from 1189. Richard's moniker is well deserved: he was commanding an army from the age of 16, and was a central commander of the Christian forces during the Third Crusade. However, he preferred to treat England as a source of revenue for his armies, spending possibly as little as six months here in all of his ten year reign. Reputedly, he also did not speak English, despite being born here, but instead spoke two French dialects. He communicated with his English advisors in Latin, as they did not speak French.
Also responsible for: all those tax hikes the animals hate in Robin Hood, and then selfishly died, leaving wicked Prince John as heir, despite Prince John's revolt in his absence. This, presumably, is where the Robin Hood myth's "usurper king vs true king" dichotomy comes from.
Athelred the Unready
Athelred was Edward the Confessor's father. He ruled from 978-1013, 1014-1016, first coming to power aged around ten, when members of his household murdered his teenaged brother, King Edward the Martyr (guess how he got his epithet). Athelred's kingdom was frequently raided by Danes, and in 991 he began paying tribute, called Danegeld, to the Danish King Sweyn. Athelred ordered a massacre of Danish settlers in 1003, causing Sweyn to invade England. He left in 1005, possible because of a famine, but returned in 1013, ousting Athelred, who fled to Normandy. Sweyn died suddenly in 1014, and English noblemen conspired to return Athelred to the throne. He was later succeeded by Cnut, after Cnut invaded England, won several battles and made the agreement that they would split the kingdom. Conveniently for Cnut, Athelred died soon after, making Cnut king of all England, in addition to his other territories.
"Athelred the Unready" is actually a mistranslation of his Old English name, Athelred Unraed. "Athelred" means "noble-counsel". This kind of compounding was typical with the names of the House of Wessex: see also Athelwulf (noble-wolf); Athelred (elf-counsel), Edward (rich-protection) and Edgar (rich-spear). It's actually a kind of pin: "Unraed" is an adjective for plans and stuff, and means "bad counsel". This, "Ill-advised" is probably a better translation. However, some quirk of fate has meant our language kept the pun, while lost the meaning. Cool, huh?