Kurt Wilhelm Sebastian Hensel (29 December 1861 – 1 June 1941) was a German mathematician born in Königsberg, Prussia.

He was the son of the landowner and entrepreneur Sebastian Hensel, brother of the philosopher Paul Hensel, grandson of the composer Fanny Mendelssohn and the painter Wilhelm Hensel, and a descendant of the philosopher Moses Mendelssohn.

He studied mathematics in Berlin and Bonn, under mathematicians like Leopold Kronecker and Karl Weierstrass.

Later in his life he was a professor at the University of Marburg until 1930. He was also an editor of the mathematical Crelle's Journal.

He is well known for his introduction of p-adic numbers. First described by him in 1897, they became increasingly important in number theory and other fields during the twentieth century.

Hensel's lemma, named after him