| Church of San Xoán | |
| Native Name: | Igrexa de San Xoán de Malta |
| Religious Affiliation: | Roman Catholic |
| Location: | Portomarín, Galicia, Spain |
| Organizational Status: | Church |
| Architecture Style: | Romanesque |
The Church of San Xoán (or Saint John) of Portomarín is a temple-fortress of the Order of St John of Jerusalem, in the Galician town of Portomarín, Spain.
It is an unusual Late Romanesque temple as it is designed to be both a church and a castle and so has architectural characteristics of both buildings. As a church it has one barrel vaulted nave, a semicircular apse and all the typical decorations of Romanesque churches; these include a carved portal with archivolts, rose windows and carved capitals. As a castle its perimeter is surrounded by merlons, it has four defense towers (one at each corner) while behind it lies an adarve, a defensive street. The north west tower currently has a stork's nest with two young (2011). The church was relocated to its current position from the valley in the 1960s when the river was flooded to form a reservoir.
It is situated on the principal route of the Way of St. James to Santiago de Compostela, where other Templar and Knight Hospitaller churches and castles were constructed as a result of the effort of the Hospital Orders to protect the way to the tomb of Santiago; others include the churches of Torres del Río, Eunate and the Castle of Ponferrada.