Callias (Greek: Kαλλίας) was an ancient Athenian aristocrat and political figure. He was the son of Hipponicus and the daughter of Megacles (she later married Pericles), an Alcmaeonid and the third member of one of the most distinguished Athenian families to bear the name of Callias. He was regarded as infamous for his extravagance and profligacy.
Historians sometimes designate him "Callias III" to distinguish him from his grandfather Callias II and from his grandfather's grandfather Callias ("Callias I").
Callias' family was unusually wealthy: the major part of their fortune came from the leasing of large numbers of slaves to the state-owned silver mines of Laurium. In return, the Calliai were paid a share of the mine proceeds, in silver. Accordingly, they were considered the richest family in Athens and quite possibly in all of Greece, and the head of the family was often simply referred to as "ho plousios" (Greek: "ὁ πλούσιος", "the wealthy"). The only other family that could rival their wealth were the tyrants of Syracuse.
Callias must have inherited the family's fortune in 424 BC, which can be reconciled with the mention of him in the comedy the Flatterers of Eupolis, 421 BC, as having recently entered into his inheritance. In 400 BC, he was involved in an attempt to destroy the career of the Attic orator, Andocides, by charging him with profanity in having placed a supplicatory bough on the altar of the temple at Eleusis during the celebration of the Mysteries. However, according to Andocides, the bough was actually placed there by Callias himself.
In 392 BC, he was placed in command of the Athenian heavy-armed troops at Corinth on the occasion of their defeat of a Spartan regiment, or Mora, by Iphicrates. Callias was hereditary proxenus (roughly the equivalent of the modern consul) to Sparta, and, as such, was chosen as one of the envoys empowered to negotiate a peace with Sparta in 371 BC. On this occasion Xenophon reports that Callias gave an absurd and self-glorifying speech.