Joseph W. Mongan (11 March 1880 – 12 March 1951) was an Irish politician. He was an unsuccessful candidate at the June 1927 general election, but was elected to Dáil Éireann as a Cumann na nGaedheal Teachta Dála (TD) for the Galway constituency at the September 1927 general election. He was re-elected at the 1932 general election but lost his seat at the 1933 general election. At the 1937 general election, he was elected as a Fine Gael TD for the Galway West constituency. He was re-elected at each subsequent general election and served until his death in 1951.