The Acts of Peter is one of the earliest of the apocryphal Acts of the Apostles in Christianity, dating to the late 2nd century AD. The majority of the text has survived only in the Latin translation of the Codex Vercellensis, under the title Actus Petri cum Simone ("Act of Peter with Simon"). It is notable for a description of a miracle contest between Saint Peter and Simon Magus, the first record of the tradition that Saint Peter was crucified head-down, and as the origin of the saying Quo vadis?

The Acts of Peter were originally composed in Koine Greek during the second half of the 2nd century, probably in Asia Minor. The style of the Acts' writing is quite similar to that of four other apocryphal Acts – Acts of Andrew, Acts of John, Acts of Paul, and Acts of Thomas. For this reason, all five of these works were traditionally attributed to a single author; Photios I (c. 810/820 – 893) identified this author as Leucius Charinus. Epiphanius (c. 310/320 – 403) had earlier identified Leucius as a companion of John the Apostle.

The Manicheans are believed to have collected these five apocryphals Acts into a single corpus by the end of the 4th century. The current consensus is that the five works are interrelated, but were written by five separate authors, none of whom include Leucius. Despite this, the works are still frequently referred to as the "Manichean Acts of Leucius Charinus", or simply the "Leucian Acts".

The earliest extant manuscript of the Acts of Peter is a Late Latin translation contained in the Codex Vercellensis, which is believed to be the earliest manuscript of the Vetus Latina. This codex is preserved in the Capitulary Library of the Vercelli Cathedral. The chapters describing Peter's crucifixion (XXXIII–XLI) are preserved separately as 'Martyrdom of the Holy Apostle Peter' in various manuscripts in Latin, Greek, Coptic, Slavonic, Syriac, Ethiopic, Armenian, and Arabic.

It has been proposed that the martyrdom account was an earlier, separate text to which the preceding chapters were affixed.^{[citation needed]}

In the text, Peter performs many miracles, such as healing a crippled beggar. Peter preaches that Simon Magus is performing magic in order to convert followers through deception. Outraged, Peter challenges Simon to a contest, in order to prove whose works are from a divine source and whose are merely trickery. In the contest, Simon takes flight, and in retaliation, Peter strikes him down with the power of God, praying that Simon not be killed but badly injured. Simon is then taken to Terracina to one Castor "And there he was sorely cut (Lat.[in Latin] by two physicians), and so Simon the angel of Satan came to his end."

Peter's confrontation with Simon Magus has some resemblance to the Prophet Elijah's confrontation with the Priests of Baal, as depicted in the Old Testament's Book of Kings – a text with which the writer of the Acts of Peter was likely familiar.

Following this incident, Peter plans to flee the city; however, he sees an apparition of Jesus, and takes it as a message that he must stay and be crucified to see Jesus again in Heaven (see Quo vadis?).