Marcus Erucius Clarus (fl AD 2nd Century), was a suffect consul (AD 117) and influential as a friend and supporter of famous Silver Age author Pliny the Younger.
Clarus was described by the Younger Pliny as a man of honor, integrity and learning, as well as skilled in pleading cases. He accompanied the Emperor Trajan on his campaign against Parthia, where he distinguished himself by defeating a Parthian army near Seleucia, killing its general Sanatruces. For this achievement he was appointed suffect consul with his fellow general, Tiberius Julius Alexander Julius in 117.
He was the brother of Gaius Septicius Clarus, prefect of the Praetorian Guard under Hadrian. Based on the similarities of their names, Clarus may be the father of Sextus Erucius Clarus, twice consul and Urban prefect.