The Maria Theresa thaler (MTT) is a silver bullion coin that has been used in world trade continuously since they were first minted in 1741, at that time using the then-standard Reichsthaler value of nine thalers to the Vienna mark.

The thaler had been debased in 1750 to ten thalers to the Vienna Mark (a weight approximating half a pound of fine silver).

The new standard is effectively adopted across the German-speaking world when that standard is accepted formally in the Bavarian monetary convention the following year.

It is owing to the date of the Bavarian Monetary convention that many writers erroneously state that the Maria Theresa Thaler was first struck in 1751.

Named after Empress Maria Theresa, who rules Austria, Hungary, and Bohemia from 1740, the word thaler gives rise to daalder and daler, which will become dollar in English.