Marcellus the Historian was a Hellenistic historian of the 3rd century BCE, known only from fragments. He is distinct from the later iambic poet Marcellus of Side. His work places him within the Greek tradition of Alexander historiography, though his precise origins are unknown.

His only known work is a History of Alexander the Great, which survives in fragments. It is preserved through quotations in later authors, primarily Aulus Gellius and the Byzantine patriarch Photius. The fragments indicate it narrated events from Alexander’s life and campaigns.

Marcellus is a minor source within the Alexander vulgate tradition. His value lies in representing one of many lost accounts that shaped the posthumous Alexander legend. The cited fragments, often anecdotal, illustrate the evolution of this tradition, though the scant remains preclude firm assessment of his reliability.