Haplogroup K or K-M9 is a genetic lineage within human Y-chromosome DNA haplogroup. A sublineage of haplogroup IJK, K-M9, and its descendant clades represent a geographically widespread and diverse haplogroup. The lineages have long been found among males on every continent except Antarctica.
The direct descendants of Haplogroup K1 (L298 = P326, also known as LT) and K-M9 are Haplogroup K2 (formerly KxLT; K-M526).
Y-DNA haplogroup K-M9 is an old lineage that arose approximately 47,000-50,000 years ago. Geneticist Spencer Wells had argued that because haplogroup K has a geographically wide distribution, the lineage probably originated near the central part of this range in the Middle East or Central Asia, possibly in Iran or Pakistan.
Basal K* is exceptionally rare and under-researched; while it has been reported at very low frequencies on many continents it is not always clear if the examples concerned have been screened for subclades. Confirmed examples of K-M9* now appear to be most common amongst some populations in Island South East Asia and Melanesia; it is also found in 2% of Italians, with frequencies reaching 8% among the Ladin people. K-M9* was also found in one individual from the Spanish province of Castellón with the surname Ferrer, and is common among the Bnei Menashe, a community of Indian Jews who claim descent from one of the Lost Tribes of Israel.
Primary descendants of haplogroup LT are L (M20), also known as K1a, and T (M184), also known as K1b.
The descendants of haplogroup K2 include: