John William Friso is the most recent common ancestor of what
Dutch monarchs family tree The following is a family tree for the Princes of Orange, a line which culminated in the Dutch monarchy with the accession of Prince William VI to the newly created throne of the Netherlands in 1815. Dates given are those of birth and death; for Princes of Orange (shown in bold), the intermediate date is the date of accession to the Princedom. By virtue of his marriage to Mary II of England, Prince William III, himself a grandson of Charles I of England, became King of England 1689–1702 (jointly with Mary II until her death in 1694) following the overthrow of his uncle and father-in-law James II of England in the Glorious Revolution. The family lineage is of note as John William Friso is the most recent common ancestor of all the current monarchs of Europe.
Neithon of Alt Clut 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.