Saxe-Gotha (German: Sachsen-Gotha) was a state in today's Thuringia, Germany.
It was created in 1640 for Duke Ernest I and ended in 1680 when his lands were divided after his death in 1675. The area around Gotha passed to Ernest's eldest surviving son, Frederick of Saxe-Gotha-Altenburg, who also inherited Altenburg (which Ernest had inherited through his wife Elisabeth Sophie) and became Duke of Saxe-Gotha-Altenburg.
When the house of Saxe-Gotha and Altenburg became extinct in 1825, Saxe-Gotha-Altenburg was split. Saxe-Gotha passed to the Duke of Saxe-Coburg-Saalfeld who in turn gave Saalfeld to Saxe-Meiningen. The Duke of Saxe-Hildburghausen became Duke of Saxe-Altenburg, and gave Saxe-Hildburghausen to Saxe-Meiningen.
After the abolition of German monarchies at the end of the First World War it became a part of the newly created state of Thuringia in 1920.