Kamehameha I the Great (1758 (?)-1819) was the first king of a united Hawaiian Islands. Although there is some debate as to the precise year of his birth, Hawaiian legends claimed that a great king would one day unite the islands, and that the sign of his birth would be a comet. Halley's comet was visible from Hawai'i in 1758, and it is therefore assumed that Kamehameha was born shortly after its appearance.
Raised in the royal court of his uncle Kalaniopuu, king of the island of Hawai'i, Kamehameha achieved prominence in 1782, upon Kalaniopuu's death. While the kingship was inherited by Kalaniopuu's son Kiwalao, Kamehameha was given a prominent religious position, guardianship of the god of war, in recognition of his prowess. Nevertheless, there was already bad blood between the two cousins, and when a group of chiefs from the Kona district offered Kamehameha the kingship instead of Kiwalao, he accepted eagerly. Kiwalao was soon defeated in battle, but the island itself was divided into rival fractions, locked in a civil war that eventually engulfed the neighboring islands of O'ahu and Maui as well. Other help came from British and American traders, who sold guns and ammunition to Kamehameha. By 1810, with the surrender of the king of Kaua'i, Kamehameha emerged as the sole sovereign of the island chain.
As king, he took several steps to ensure that the islands remained a united realm even after his death. He unified the legal system and he used the products he collected in taxes to promote trade with Europe and the United States. This ensured the islands' independence even while many of the other islands of the Pacific succumbed to the colonial powers. In fact, the Kingdom of Hawaii that Kamehameha established retained its independence, except for a five-month British occupation in 1843 until it was annexed by the United States in 1898. It was this legacy that earned Kamehameha the epithet "Napoleon of the Pacific."
The Kamehameha Wave is an "attack" in the Animes Dragon Ball, Dragon Ball Z, and Dragon Ball GT. It was not named after the Hawaiian King, but is in fact Japanese for "Turtle Destruction Wave".