San Nicola in Carcere (Italian, "Saint Nicholas in prison") is an ancient titular church and minor basilica in Rome near the Forum Boarium in rione Ripa.

The inscriptions found in S. Angelo, a valuable source illustrating the history of the Basilica, have been collected and published by Vincenzo Forcella.

The columns of the Temple of Janus, dedicated by Gaius Duilius after his naval victory at the Battle of Mylae in 260 BC,[2] can still be seen as being incorporated into the northern wall of the church.

In the 11th century, it was known as the church of Petrus Leonis, referring to the converted Jewish family, the Pierleoni, who rebuilt the nearby Theatre of Marcellus as a fortress.

One of their members, Pietro Pierleone, was an important cardinal in the 1120s and was elected Pope Anacletus II, though he was later branded a schismatic antipope.