Johan Harald Josua (Joshua) Lindahl (January 1, 1844 – April 19, 1912) was a Swedish American geologist and paleontologist. He was a professor at Augustana College from 1878 to 1888, then was Illinois State Geologist until 1893. He is the namesake of the extinct Cyprinidae subspecies Aphelichthys lindahlii. and the extinct Medullosales Neuropteris lindahli named by David_White_(geologist)