Frederick I of Saxe-Gotha-Altenburg

Frederick I, Duke of Saxe-Gotha-Altenburg, was a territorial ruler in Thuringia from the Ernestine branch of the House of Wettin. He continued the line of Saxe-Gotha founded by Ernest I, his father, which, to distinguish it from the older Gotha line, is generally referred to as Saxe-Gotha-Altenburg.