Dermot O'Mallun, 1st Baron Glean-O'Mallun (died 1 May 1639) was an Irish lawyer.
A Roman Catholic, he was educated abroad and became learned in the law and in poetry. He served as a lawyer to the Archdukes Albert and Isabella of the Spanish Netherlands, and in 1616 he was made a knight of the Order of Calatrava.[1] He also served as an equerry to the Infanta Isabella, as a gentleman of the chamber to the Emperor Ferdinand II, and as mestre de camp of a regiment of cavalry in the Emperor's service.[2] On 5 October 1622 he was raised to the peerage of Ireland by King James I as Baron Glean-O'Mallun and Courchy of county Clare, with remainder to Albert O'Mallun and his heirs male.[3]
O'Mallun was married to Marie Hannedouche, dame de Haguerve, daughter of Sebastien Hannedouche, seigneur de Hunctun, de Faye et de Bondues, and his wife Michelle de Hauteclocque. They had a daughter Anne Marie, who married Jacques Quarré, seigneur de La Haye, and had issue. O'Mallun died on 1 May 1639 and was buried in the Church of St Gudule at Brussels. His widow died on 1 February 1641.[2]
Nothing further is known of the barony, which probably became extinct in about May 1641. However, one Dermot Malone sat under this title in the Patriot Parliament of 1689.[4] [5]