R-L151, also known as R-L11 and R1b1a2a1a, is a human Y-chromosome DNA haplogroup; a subclade of the broader haplogroup R1b (R-M343).^[1] It is most often found in males from Western Europe – especially Western France, Northern Spain, Great Britain, and Ireland.^{[citation needed]}

This haplogroup is related to the period of Corded Ware or Beaker culture, and possibly founded 3,000 years before our era in the Central part of Europe (possible Bohemia region).^{[citation needed]}

R-L151 is the most populous branch of R-M269, and is found in abundance along the Atlantic coasts of western Europe, especially Aquitaine, Asturias, Basques, Belgium, Brittany, Galicia, England, Ireland (as a whole), the Loire region, the isle of Man, Northern Portugal, Northern Spain, Scotland, and Wales.^[2] It is also found at significant levels in Switzerland and Northern Italy. R-L151 is found at lower frequencies in Poland and Ukraine, as well as many other European countries.^[3] Since the early modern era, males emigrating from Europe have introduced significant levels of R-L151 to The Americas and Australasia.

This human haplogroup has two subclades, the south-western branch, P312/S116, and the north-eastern branch, R1b-S21-U106.