Johannes (Hans) Gottfried Hallier (6 July 1868 – 10 March 1932) was a German botanist born in Jena. He studied botany and zoology at the University of Jena under Christian Ernst Stahl (1848–1919) and Ernst Haeckel (1834–1919), and continued his studies at the University of Munich under Ludwig Radlkofer (1829–1927) and Richard Hertwig (1850–1937). From 1893 until 1897, he was based at the Buitenzorg Botanical Garden in Java. He died on 10 March 1932 in Oegstgeest, Netherlands. Hallier is commemorated in the scientific name of a species of lizard, Tytthoscincus hallieri.