Atticus was a Platonist philosopher active in the Roman Empire during the 2nd century CE, most likely during the reign of Emperor Marcus Aurelius. His exact birthplace and the location of his school are uncertain, with some scholars suggesting Athens and others a location in the Eastern Empire. He is known primarily as a fierce defender of Plato's philosophy against rival schools.

His significance lies in his strong opposition to the common practice of harmonizing Plato's teachings with those of Aristotle. Atticus wrote a single major work, now lost, arguing that Aristotle's ideas on the eternity of the world, the soul, and ethics were fundamentally incompatible with Plato's. Modern scholars often refer to this polemical text as Against Those Who Claim to Interpret Plato through Aristotle. The work survives only in fragments, preserved mainly by the 5th-century Christian writer Eusebius, who found Atticus's criticisms useful for his own arguments.

According to modern scholars, Atticus represents an important "purist" strand within Middle Platonism. His fragments provide crucial evidence for the intense debates about Plato's legacy before the rise of Neoplatonism. His arguments were influential enough to be engaged with by later philosophers, securing his place as a notable, if fragmentary, voice in ancient philosophical history.