The Cathedral Church of St Mary and St Thomas is a Roman Catholic cathedral in Northampton, England.

The origins of the current building date back to 1840 when Augustus Pugin designed the collegiate chapel of St Felix. Edward Pugin designed an extension in order to make the building into a cathedral. This extension came in the form of the current nave, which was opened in 1864. Dating from the 1860s, the stained glass windows were made by John Hardman of Birmingham. Between 1948 and 1955, the cathedral was further enlarged.