Archduke Maximilian III of Austria, also known as Maximilian der Deutschmeister (born October 12, 1558 in Wiener Neustadt; died November 2, 1618 in Vienna) was the third son of Emperor Maximilian II.

From 1585 onwards, he was the Grand Master of the Teutonic Order and administrator of Prussia. In 1587, he was to become King of Poland. He was elected, but lost to Sigismund Wasa. When he attempted to resolve the dispute by military force, he was defeated and captured by the Polish general Jan Zamojski, only after intervention by the pope. In 1589, he waived his right to the Polish crown. The inactivity of his brother Rudolf II in this matter contributed to Rudolf's bad reputation.

From 1593 to 1595 he was Regent in Inner Austria, and subsequently in Tyrol, where he proved to be a consequent proponent of the counterreformation. He also worked to dispose Melchior Khlesl, and worked to ensure that Archduke Ferdinand of Inner Austria would succeed as Holy Roman Emperor.

He most known legacy is the baroque Archduke's Hat, which is exhibited in the treasure chamber of the monastery of Klosterneuburg and was used for ceremonial purposes as late as 1835.

|- style="text-align: center;" | width="30%" |Preceded by:
Heinrich VIII von Bobenhausen | width="40%" style="text-align: center;" |Grand Master of the Teutonic Order
1590-1618 | width="30%" |Succeeded by:
Karl I of Austria