Jan Hendrik Wakker (28 June 1859 – 26 July 1927) was a Dutch botanist and plant pathologist.
He then went to study under Hugo de Vries and J.C Costerus and received a doctorate in 1885 with research on adventitious buds.
He then worked with Hugo de Vries, examining a disease of hyacinths caused by bacteria.
In 1892 he received an appointment as director in the Dutch East Indies sugarcane experimental station in Pasoeroean where he worked for five years.
In 1905 he was offered a directorship at the Willie Commelin Scholten Phytopathology Laboratory but he did not accept it.