St. Catherine's Old Church (Maltese: Knisja ta' Santa Katerina l-Antika), also known as St. Gregory's Church (Maltese: Knisja ta' San Girgor), is a Roman Catholic church in Żejtun. The church and its complex sit towards the outskirts of the town, commanding views over Marsascala Bay, St. Thomas' Bay and Marsaxlokk harbour. The church is colloquially known as Saint Gregory's due to a traditional procession held on the first Wednesday following Easter Sunday. Its dedication to Catherine of Alexandria dates back to an original chapel on this site, which was one of the eight mother churches on Malta. The church stands next to the three cemeteries of Żejtun, dedicated to St. Rocco, St. Gregory and St. Catherine. The church's functions as the parish church of Żejtun were taken over by a new parish church, also dedicated to St. Catherine, and designed by Lorenzo Gafà.