Probably the most famous of the Anglo-Saxon kingdoms and one of the oldest. Wessex - 'west Saxons'.
The legend of the founding of Wessex begins in 495 when Cerdic and Cynric landed in Britain with five ships. Then Port, and his two sons Bieda and Maegla landed at Portsmouth (named after Port, no doubt) in 501 and killed somebody very high-ranking. A few years later, Cerdic killed a British king called Nantenleod and five thousand of his men. Cerdic thus became the first king of Wessex.
This is the story according to the Anglo-Saxon Chronicle. There is archaeological evidence that Anglo-Saxons settled in the south and east coast of England around this time, although there are no records of a King Nantenleod. The kingdom of the west Saxons became Wessex and one of the most significant kingdoms in the heptarchy. It also had the only English king to be known as 'The Great' - Alfred.
What Alfred achieved was a unified England. Wessex was the only kingdom to survive the Viking raids as the forces known as the Great Heathen Army overpowered Northumbria, East Anglia and half of Mercia. In 886 Alfred declared a truce with the Danes that split the country, with the Vikings ruling the east and north, and the unified England ruling the south.
Danish attacks continued against Wessex and Mercia but they lost out to the hosts. After the death of the rulers of Mercia - Alfred's daughter and son-in-law - Edward, Alfred's son, took over and Mercia was no more an independent kingdom. In 927, the Wessex King Aethelstan conquered Northumbria and therefore all of England was under one ruler. On 12 July all monarchs agreed that Aethelstan should be the king of England. Wessex, the last Anglo-Saxon kingdom, was no more. But, like many of the other former kingdoms, it has kept its own dialect and culture to this day.
The former kingdoms became earldoms but that became irrelevant when William the Conqueror arrived in 1066...