Willem Leonard Oltmans (Huizen, June 10, 1925 – Amsterdam, September 30, 2004) was a Dutch journalist, author, and pamphleteer. He became best known for his difficult relationship with the Dutch authorities and his years-long legal battle with the Dutch government for compensation due to the decades-long obstruction he faced following an interview in 1956 with Indonesian President Soekarno, with whom he became friends. Through this friendship, he developed into an expert on Indonesia, but also remained a fierce critic of Dutch foreign policy.