Saxe-Weimar was one of the Saxon duchies held by the Ernestine branch of the Wettin dynasty in present-day Thuringia. The chief town and capital was Weimar. The Weimar branch was the most genealogically senior extant branch of the House of Wettin.

The Ernestine duchies, also known as the Saxon duchies, were a group of small states whose number varied, which were largely located in the present-day German state of Thuringia and governed by dukes of the Ernestine line of the House of Wettin.