Lupiac (French pronunciation: [lypjak]) is a commune in the Gers department in southwestern France.

The Auzoue forms most of the commune's southeastern border.

The Douze forms the commune's western border.

Charles de Batz de Castelmore d'Artagnan (c. 1611 – 25 June 1673), a captain of the Musketeers of the Guard, was born here.

A fictionalized version of his life is central to The Three Musketeers by Alexandre Dumas, père.