Cuthbert Welby Pugin (1840–1928) was a British architect. He was the son of Augustus Welby Pugin and his second wife Louisa Button, making him Pugin's fourth child and second son. He was brother of Edward Welby Pugin and Peter Paul Pugin, also both architects. He is most notable for his design of St John the Evangelist, Poulton-le-Fylde and his collaborations with Peter Paul to complete St Anne's Church, Highfield Road and Heart of Jesus, Kilburn to designs by Edward. All three brothers also made additions and alterations to The Grange, Ramsgate, originally designed by their father.
In 1860 he became manager of the South East Furniture Company, founded by Edward to manufacture Edward's designs. He began assisting Edward in the 1860s and he and Peter and Paul took over the English and Scottish work of Pugin & Pugin in 1873 when Edward had to flee to the USA to escape his creditors. When Edward died in 1875, Peter Paul took over main responsibility for the firm, with Cuthbert focussing on its furniture-making and furnishing sides until 1880, when he withdrew to run the family's furniture workshops directly. He lived in retirement in the Grange in Ramsgate until his death in 1928.