John FitzGerald, de facto 12th Earl of Desmond

John FitzGerald, de facto 12th Earl of Desmond (died December 1536) was the brother of Thomas FitzGerald, 11th Earl of Desmond. Upon his brother's death in 1534, John disputed the title to the earldom of his brother's grandson, James FitzGerald, de jure 12th Earl of Desmond.

John FitzGerald
Earl of Desmond
Tenure	1534-1536
Predecessor	Thomas FitzGerald, 11th Earl of Desmond
Successor	James FitzGerald, de jure 12th Earl of Desmond
Died	December 1536
Spouse(s)	Móre O'Brien
Issue Detail	James FitzGerald, 13th Earl of Desmond & others
Father	Thomas FitzGerald, 7th Earl of Desmond
Mother	Ellice de Barry

Ireland in 1450, showing the Earldom of Desmond

According to the Annals of the Four Masters, John FitzThomas FitzGerald was believed to have instigated the murder of his older brother, James FitzGerald, 8th Earl of Desmond in 1487, and had been expelled by his brother Maurice FitzGerald, 9th Earl of Desmond.

John died in 1536. His grandnephew, the de jure earl, died in 1540, and was succeeded by John's son, James FitzGerald, 13th Earl of Desmond.

Alfred Webb tells us of this earl that he, "being supported by a large faction, was de facto [12th] Earl. This Sir John died about Christmas 1536."

Ancestors of John FitzGerald, de facto 12th Earl of Desmond
Gerald FitzGerald, 3rd Earl of Desmond James FitzGerald, 6th Earl of Desmond Eleanor Butler Thomas FitzGerald, 7th Earl of Desmond Mary de Burgh John FitzGerald, de facto 12th Earl of Desmond John FitzDavid Barry, 7th Baron Barry William Barry, 8th Baron Barry Ellice FitzGerald Ellice de Barry Ellen de la Roche