Jan Willems, also known as Janke or Yankey Willems, (d. 1688) was a 17th century Dutch buccaneer. Based out of Petit Goave, Willems participated in a number of expeditions against the Spanish during the early to-mid 1680s with other well-known privateers including Michiel Andrieszoon, Thomas Paine, Laurens de Graaf, Nicholas van Hoorn and Michel de Grammont.
Willems, along with Laurens de Graaf, Nicholas van Hoorn and Michel de Grammont, successfully raided Vera Cruz on May 17, 1683. Using two captured Spanish galleons in the vanguard, he and Laurens de Graaf were able to sneak into the Spanish harbor during the early morning hours and landed a small force on shore. The buccaneers caught the garrison off guard, many of the soldiers still sleeping, and took out the city's defenses allowing the rest of the fleet to enter the harbor. After three or four days, Willems and the others looted the town before retreating at the sight of the New Spain fleet. In late-November, he joined Michiel Andrieszoon, Francois Le Sage and Laurens de Graaf in attacking Spanish shipping off Cartagena resulting in an altercation with Governor Juan de Pando Estrada who commandeered two Spanish slavers to go after them.
He participated in de Graaf's later raids against Cartagena in 1684 and Campeche in 1685. After the raid on Cartagena, de Graff gave Willems his old flagship, the Princesa. Willems reportedly died in the Gulf of Honduras in 1688.