Stift Sankt Peter or St Peter's Archabbey, is a Benedictine monastery in the Austrian city of Salzburg. It is considered one of the oldest monasteries in the German-speaking area, if not in fact the oldest.

Stift Sankt Peter was founded in 696 by Saint Rupert at the site of a Late Antique church stemming from the first Christianization in the area in the days of Severinus of Noricum. Likewise the establishment of the monastery was meant to forward the missionary work in the Eastern Alps. Until 987, the office of the abbot was joined to that of the Archbishop of Salzburg: the two were always held together by one man.

Stift Sankt Peter houses the oldest library in Austria. Among the 800 manuscripts the most precious is the Verbrüderungsbuch, which was deposited in 784 by Bishop Virgil. Through continual acquisition, the library has grown to 100,000 volumes, focusing particularly on Benedictine monasticism, medieval church history, history of art, and items relating to the local history of Salzburg, or Salisburgensia. Special collections include incunabulae and early editions, graphics including the devotional images collection of Father Gregor Reitlechner and the map collection.

The present-day Romanesque building at the northern foot of the Mönchsberg was dedicated in 1147. One of the organs had been built on the rood screen in 1444 by Heinrich Traxdorf of Mainz. While the steeple received its onion dome in 1756, the interior, already re-modelled several times, was refurbished in the Rococo style between 1760 and 1782 under Abbot Beda Seeauer by Franz Xaver König, Lorenz Härmbler, Johann Högler, Benedikt Zöpf and others. The high altar is a work by Martin Johann Schmidt. The St Mary's Chapel contains the grave of Abbot Johann von Staupitz (d. 1524), a friend of Martin Luther.