Alexander Stewart, 6th Earl of Galloway was a Scottish aristocrat.

Earl of Galloway is a title in the Peerage of Scotland. It was created in 1623 for Alexander Stewart, 1st Lord Garlies, with remainder to his heirs male bearing the name and arms of Stewart. He had already been created Lord Garlies in the Peerage of Scotland in 1607, with remainder to the heirs male of his body succeeding to the estates of Garlies. This branch of the Stewart family were distant relatives of the Stewart Kings of Scotland.