The purpose of the Langan surname project is to identify the ancestral origins and migrations (i.e. main haplogroups) of the Langans and similar sounding names and, hopefully, discover some closer genealogical relationships from the available Y-DNA databases.

The name Langan is a contraction and Anglicisation of the Irish (Gaelic) name, Ó Longáin, meaning grandson (or descendant) of Longáin.  Longáin is thought to mean long or tall.