(Πρόθοος), a son of Tenthredon, commander of the Magnetes who dwelt about amount Pelion and the river Peneius, was one of the Greek heroes at Troy. (Hom. Il. 2.758.) There are three other mythical personages of this name, one a son of Agrius (Apollod. 1.8.6), the second a son of Lycaon (3.8.1), and a third a son of Thestius and brother of Althaea. (Paus. 8.45.5, who calls him Πρόθους.)
[L.S]A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890