Joseph J. Costello (1892–1960)[citation needed] was the longest serving Mayor of Galway.

Costello first entered public life when elected to the Galway Urban Council in 1924.

The last mayor, prior to Costello's tenure, was Edmond Blake, who held office until 1841 when the position was dissolved.

Costello was the town's longest serving mayor, and his term of office lasted from December 1937 until September 1950.

During this time, he granted the Freedom of Galway to Douglas Hyde and Éamon de Valera, set up the 'Mayor's Fuel Fund' to help address fuel poverty, and oversaw the return of the body of William Butler Yeats in 1949.