|Arturo O'Neill de Tyrone y O'Kelly|
|1st Spanish Governor of West Florida|
May 9, 1781 – November 1792/1794
|Preceded by||Peter Chester (British West Florida (1763-1784))|
|Succeeded by||Carlos Howard|
|93º Colonial Governor of Yucatán|
March 10, 1792 – 1794
|Lieutenant||Benito Pérez Valdelomar|
|Preceded by||Jose Sabido de Vargas|
|Born||January 8, 1736
|Died||December 9, 1814.
|Profession||colonel and Political|
Arturo O'Neill de Tyrone y O'Kelly (January 8, 1736 – December 9, 1814) was an Irish-born Spanish colonel who served the Spanish crown as governor of several places in New Spain (1781–1794). He came from a lineage that occupied prominent European positions and titles, beginning, at least, in the 12th century.
Early years and Military career
Arturo O'Neill was born in Dublín, Ireland (although his ancestors were from Tyrone, county of Northern Ireland), in January 8, 1736. He was third of the five children of Henry O´Neill and Ana O´Kelly. One of his brothers was Lieutenant Colonel Niall O'Neill (later Nicolás O'Neill y O'Kelley). His family lost their lands in Ireland, forcing them to emigrate. So, his parents carried Arturo and his brothers to Spain. In 1752, O'Neill, when he was still youth, joined to Irish regiment, in Ireland, as a cadet, under obedience to their cousin, the regimental commander José Camerford.
In 1753, O'Neill moved to Regiment of Hibernia, to which belonged for the next twenty-eight years of his military career. He joined to this regiment when he was still very young during the reign of Charles IV of Spain. He was sub-lieutenant nine years and he achieved also grades of Lieutenant general and field marshal. He served in the campaign of Portugal, in 1762. He was then in garrison of Oran and later, in 1775, in the military campaign of Algiers. He was also present in the campaign against Brazil, which contributed to the seizure of Fort Santa Cruz, Santa Catalina Island, which served as governor until the end of the war.
His military skills enabled him to obtain, in 1764, promotion to Assistant Mayor of Hibernia and, in 1773, while serving in Pamplona, Spain, O'Neill obtained the rank of captain of the regiment. In addition, he was promoted also to colonel of the Regiment of Hibernia after serving with distinction against the British at Pensacola in March 1781. 
Governor of Florida
At the battle's conclusion, on May 9, 1781, he was appointed governor of Spanish West Florida in the service of New Spain, proving to be an effective diplomat and an able administrator. Later he became a member of the Supreme War Council and a lieutenant general of allies against Napoleon, replacing the governor Miguel de Uztaraiz on the council. Between May 31 and June 1, 1784, O'Neill participated in the Conference of Creeks, where Spain and Creeks signed a treaty of friendship, being the host of the conference.
In addition, Creeks, Chickasaws and Cherokees sought help from O'Neill to defend them against the U.S. invasion, so the Irish military and governor sent reinforcements to the areas of this peoples. In 1786, McGillivray informed O'Neill that the Americans were trying to get friendship by the Creeks, so, fearing that the alliance could be detrimental to the Spanish in the West Florida, decided to fight back, setting another treaty with Amerindians in Mobile (modern Alabama).
In late 1787, O'Neill, based on the fact that he had ruled Florida for 6 years (when it was customary five), asked the Spanish crown that he ascended to the title of brigadier and the Governor of Puerto Rico or in a similar position, but he did not receive the requested transfer.
However, his health began to fail in 1788 and O'Neill asked the Spanish crown temporarily absent to be able to recover. The crown accepted and O'Neill was replaced as Governor by Francisco Cruzat, former lieutenant governor of Illinois. In addition, he was promoted to brigadier general in 1789.
On March 10, 1792 Arturo O'Neill became Marqués del Norte (Marquis of North).
In order to defend Florida and help the guard there, he recommended creating, at least, six Amerindian companies formed by 100 people each. Along to Amerindianas, the Mestizos belong also to those companies.  In addition, O'Neill wanted increase the Mestizo´s number proposing marriage between the Spanish and the Native Americans, because he considered that Mestizos kept more friendly relationship with whites. To do this, he wanted to send a missionary to the Native American villages and encourage miscegenation between the Spanish and Christian Amerindians. In addition, he considered Mestizos as an important group in terms of military and economy. 
He left the office of Governor of West Florida in November 1792.
Governor of Yucatan and last years
To following month, on December 13, 1792, he was appointed governor and captain general of Yucatan, and Intendent de Tabasco y la Laguna de Términos, but the office of Governor was expanded him with the quartermaster on January 20, 1793, taking over possession of it on June 29, 1793. He replaced Joseph Sabido de Vargas, who held the position of Interim, following the murder of the owner Lucas de Galvez, which occurred on June 22 last year. During his government he took urgent measures to prevent the spread of the rabies that came to represent a public health risk in the Yucatan. He expanded the supply of teachers for schools and also had to tackle smuggling that was done from across the province of Cuba and the islands the Caribbean Sea.
He faced harassment by English buccaneers in Walix (Belize) where he led an expedition which resulted in bad end to the belief that England had conquered eastern territories of the Peninsula. He carried out the seizure of the ship, La Bella Jane in San Francisco de Campeche.
In 1794, O'Neill stepped down as governor of West Florida and was replaced later by Enrique White. He wrote a book entitled Description, population and census of the Province of Yucatan in New Spain in 1795, which was never printed.
He served as governor of Yucatan until October 19, 1800, where he gave it to Benito Perez Valdelomar. Back in Madrid was appointed Minister of the Royal and Supreme Council of War. His last position was as a soldier in the army of Spain against Napoleon.
One of his sons was Patrick O'Neill.
- Eric Beerman (1981). "ONEILL-L Archives". Retrieved May 22–26, 2010.
- Florida Irish: Hereditary Center. ARTHUR O’NEILL. First Governor of Spanish West Florida (1781 to 1793). Retrieved on July 15, 2014, to 23:50pm.
- Casares G. Cantón, Raúl; Duch Colell, Juan; Antochiw Kolpa, Michel; Zavala Vallado, Silvio. Yucatán en el tiempo (In Spanish: Yucatan in Time). 1998. Isbn = 970 9071 04 1. Mérida, Yucatán
- Marqués del Norte, Arturo O'Neill. (in Spanish: Marquis, Arthur O O'Neill). Retrieved on March 3, 2012.
- Eric Beerman (1981). "Arturo O´Neill: First Governor of West Florida During The Second Spanish Period". JSTOR 30148550.
- Creeks & Seminoles: The Destruction and Regeneration of the Muscogulge People. Written by James Leitch Wright. Page 124.
- Mixed Blood Indians: Racial Construction in the Early South. Written by Theda Perdue. Page 73.
- U.S. States F-K.