Neithon (died c. 621) was a 7th-century ruler of
Alt Clut, the
Brittonic kingdom later known as Strathclyde. According to the
Harleian genealogies, he was the son of Guipno map
Dumnagual Hen. Alfred Smyth suggests he is the same man as King
Nechtan the Great of the
Picts, and perhaps the Nechtan son of Canu the
Annals of Ulster record as having died in 621. The
Senchus fer n-Alban indicate that Gartnait, the son of
Áedán mac Gabráin, King of
Dál Riata, sired a son named Cano, but unless the Harleian genealogies are to be ignored, this would make Gartnait and Dumnagual Hen the same persons, as the respective fathers of Gartnait and Guipno. However, it is possible that either as an Alt Clut
Briton ascending the throne of Pictland, or as a Pict ascending the throne of Alt Clut, his genealogy might have been altered, and it is notable that in the Pictish king-lists he is called "
Nechtan, nepos Uerb", suggesting that it was a descent from Uerb that mattered in Pictland, and not his unimportant father Guipno/Canu.
Alan Orr Anderson pointed out that Uerb is probably the Pictish form of
Ferb (genitive
Feirbe), a female name. Alan MacQuarrie suggests that Neithon was indeed the Pictish king Nechtan, but does not take any stance of the Guipno/Canu problem.