Antonia Minor
Marcellus was born into the Claudii Marcelli, a plebeian branch of the "gens Claudia" in 42 BC, the son of Gaius Claudius Marcellus and Octavia Minor. He had two full sisters named Claudia Marcella Major and Claudia Marcella Minor as well as two younger maternal half-sisters named Antonia Major and Antonia Minor.