James Hardiman (February 1782 – 13 November 1855), also known as Séamus Ó hArgadáin, was a librarian at Queen's College, Galway and an important historian.
Hardiman was born in Westport, County Mayo, in the west of Ireland.
His father owned a small estate in County Mayo.
He was trained as a lawyer and became sub-commissioner of public records in Dublin Castle.
In 1855, shortly after its foundation, Hardiman became librarian of Queen's College, Galway.