Pantaleon, also known as Panteleimon, (Greek: Πανταλέων) was a Greek king who reigned some time between 190–180 BC in Bactria and India. He was a younger contemporary or successor of the Greco-Bactrian king Demetrius, and is sometimes believed to have been his brother and/or subking.

Portrait of Pantaleon.
Indo-Greek king
Reign190–180 BC
PredecessorDemetrius I
Died180 BCE
King Pantaleon in profile, with Zeus on the reverse.
Agathocles commemorative coin for Pantaleon, represented on the obverse.
Cupro-nickel coin of king Pantaleon.
Obv: Bust of Dionysos with a wreath of leaves.
Rev: Panther with a small bell around the neck, touching a vine with the left leg. Greek legend: ΒΑΣΙΛΕΩΣ ΠΑΝΤΑΛΕΟΝΤΟΣ "Of King Pantaleon".

The scarcity of his coinage indicates a short reign. Known evidence suggests that he was replaced by his (probable) brother or son Agathocles, by whom he was commemorated on a "pedigree" coin.