Knights of Saint Columbanus

The Order of the Knights of Saint Columbanus (Irish: Ridirí Naomh Cholumba) is an Irish national Catholic fraternal organisation. Founded by Canon James K. O'Neill in Belfast, Ireland in 1915, it was named in honour of the Irish saint Columbanus. Initially established as a mutual benefit society for working class Catholics, it has developed into a fraternal benefit society dedicated to providing charitable services to all areas of the Irish community.

There are 68 councils across all 32 counties on the island of Ireland. Membership in the order is open to all practising Catholic men and their families aged 18 and over. There is a youth division of the order open to younger men ages 16 and up called the Associate Knights of St Columbanus. The Order is a founding member of the International Alliance of Catholic Knights.

Widely described as a secret society, the organisation rejects this assertion. The Knights of St. Columbanus has also had influence in government, business and trade unions. It has been described in Church, State and Social Science in Ireland as "the Irish organisation most durably associated with combating Catholic economic subordination," as it sought, after formation, to break through the hegemony of a Protestant minority in public institutions and commerce. It is headquartered at a Georgian clubhouse in Ely Place, Dublin.