Willem Meijer (1923 – 22 October 2003) was a Dutch botanist and plant collector.

He returned to Europe for a short leave before going back to Indonesia in February 1955.

In September 1956, Meijer was appointed the Professor of Botany at the institution.

His expertise lay in hepaticology, although he also studied mosses, ferns, and spermatophytes Meijer was repatriated in 1958.

From May 1959, he was employed by the Forest Department of North Borneo, stationed in Sandakan.