Hendrik Willem Lenstra Jr. (born 16 April 1949, Zaandam) is a Dutch mathematician.

Jan Karel Lenstra is the former director of the Netherlands Centrum Wiskunde & Informatica (CWI).

Hendrik Lenstra was the Chairman of the Program Committee of the International Congress of Mathematicians in 2010.

He is well known for: In 1984, Lenstra became a member of the Royal Netherlands Academy of Arts and Sciences.

[8] He was awarded the Spinoza Prize in 1998,[9] and on 24 April 2009 he was made a Knight of the Order of the Netherlands Lion.