De Líon
de LÍON—XI—de Leon, de Lyons, Lyon, Lyons, etc.; Norman 'de Leon,' 'de Lyons,' i.e., of Lyons, the city in France, or possibly of Lyons, a parish in Durham; the name of an Anglo-Norman family who came to Ireland about the time of the invasion and settled in Meath and other parts of the Pale.
Alphabetical Index to Irish Surnames