The heir apparent and sole heir to the peerage is the present holder's son Hon. Francois Hugh Nial O'Neill (b. 1984).[3]
Arms
Coat of arms of Baron Rathcavan
Crest
1st an arm embowed in armour the hand grasping a sword all Proper 2nd a stork rising with a snake in its beak all Proper.
Escutcheon
Quarterly 1st & 4th per fess wavy the chief Argent and the base representing the waves of the sea in chief a dexter hand couped at the wrist Gules in base a salmon naiant Proper 2nd & 3rd chequy Or and Gules a chief Vair a mullet for difference.
Supporters
On either side a heron Proper standing on a billet fesswise wavy Argent charged with a bar wavy Azure.