The family arms date back to medieval times as is attested by a small stone cross from Navan on which the Nangle family arms are carved. The cross is preserved in the National Museum in Dublin.

This is the family coat of arms of the Nagle family. The three diamond shapes (properly called "Fusils") in the centre of the shield are a common bond between the three Septs of the family.

This is the coat of arms of the Costello family. You can see that the colours of the shield and fusils are reversed from the Arms of the Nangles.

This is the coat of arms of the Nangle family. Yet again you can see the three "Fusils" in the centre of the shield that are the mark of the family as a whole.

The different branches of the family have used several motto's over the centuries. The known ones are:

• De Angulo Recto - ("Nangle in right of law")
• Non vox sed votum - ("Not by words but by deeds")
• Inimicus inimico - ("We are hostile to the enemy")
• I care not for him that cares not for me
• Prenez Garde - ("Be on your guard")