Pieter Willem Korthals (September 1, 1807, Amsterdam – March 1892, Haarlem) was a Dutch botanist. Korthals was the official botanist with the Dutch East India Service from 1831 to 1836. Among his many discoveries was the medicinal plant Kratom (Mitragyna speciosa). Korthals wrote the first monograph on the tropical pitcher plants, "Over het geslacht Nepenthes", published in 1839. The standard author abbreviation Korth. is used to indicate this person as the author when citing a botanical name.