Alexander Mack (c. 27 July 1679 – 19 January 1735) was the leader and first minister of the Schwarzenau Brethren (or German Baptists) in the Schwarzenau, Wittgenstein community of modern-day Bad Berleburg, North Rhine-Westphalia, Germany. Mack founded the Brethren along with seven other Radical Pietists in Schwarzenau in 1708. Mack and the rest of the early Brethren emigrated to the United States in the mid-18th century, where he continued to minister to the Brethren community until his death.