Ferdinand III (Spanish: Fernando; 1199/1201 – 30 May 1252), called the Saint (el Santo), was King of Castile from 1217 and King of León from 1230 as well as King of Galicia from 1231. He was the son of Alfonso IX of León and Berenguela of Castile .
Ferdinand III was elected King of the Romans at the Diet of Regensburg on 22 December, 1636. Upon the death of his father on 15 February 1637, Ferdinand became Emperor. His political adviser Trauttmansdorff advanced to the position of Prime Minister of Austria and Chief diplomat, but was replaced by Johann Ludwig von Nassau-Hadamar in 1647 as his health had begun to deteriorate.