Major-General Sir Percy Zachariah Cox, GCMG, GCIE, KCSI, KBE, DL (20 November 1864 – 20 February 1937) was a British Indian Army officer and Colonial Office administrator in the Middle East. He was one of the major figures in the creation of the current Middle East.

Cox was born in Harwood Hall, Herongate, Essex, one of seven children born to Julienne Emily (née Saunders) Cox and cricketer Arthur Zachariah Cox (né Button). He was educated initially at Harrow School where he developed interests in natural history, geography, and travel. In February 1884, being his father's third son and therefore without significant inheritance, Cox joined the Royal Military College, Sandhurst, and was commissioned as a Lieutenant into the Cameronians, joining their 2nd Battalion in India. In November 1889, an outstanding planner, he transferred to the Bengal Staff Corps. On 14 November 1889 he married Louisa Belle, youngest daughter of Irish-born surgeon-general John Butler Hamilton.

After holding minor administrative appointments in Kolhapur and Savantvadi in India, Cox was posted to British Somaliland, which was then administered from India, as Assistant Political Resident at Zeila. He transferred to Berbera in 1894. He was promoted to captain in February 1895. In May 1895 he was given command of an expedition against the Rer Hared clan, which had blocked trade routes and was raiding the coast. With only 52 Indian and Somali regulars and 1,500 poor quality, untrained local irregulars, he defeated the Rer Hared in six weeks. Later that year 1895, he was promoted to be assistant to the Viceroy of India's agent in Baroda.

For 1899 he had intended to join the US expedition under A Donaldson Smith between the River Nile and Lake Rudolf, but in October 1899, the new Viceroy of India, Lord Curzon appointed Cox Political Agent and consul at Muscat, Oman, inheriting a tense situation between the British, French and Arabs who regarded the area as under their influence. The French had leased a coaling station from Sultan Feisal, the local ruler, for the French Navy. The French also gave protection to the local slave trade, which the British opposed. Feisal was ordered by the British under Cox to board the British merchantman SS Eclipse, whose guns were trained on his palace and reprimanded and informed that his annual subsidy could be withdrawn by the British government.

Cox managed to successfully end French influence in the area; turning the subsidy around, and agreeing that Feisal's son could receive an education in England and visit the Delhi Durbar. When Lord Curzon visited Muscat in 1903, he judged that Cox virtually ran the place. Cox was promoted to the rank of major on 6 February 1902, and was invested Companion of the Order of the Indian Empire; whereas Feisal was rewarded for loyalty with Knight Grand Commander of the Order of the Indian Empire in Curzon's gift.

In June 1904, Major Cox was appointed first British Acting Political Resident in the Persian Gulf and Consul-General for Fars province, Lurestan and Khuzestan and the district of Lingah, residing in the Persian side of the gulf at the city of Bushehr. He began a remarkable correspondence and friendship with Captain William Shakespear, appointed Cox's deputy Political Resident to Persia. Their frank exchange of views at Bandar Abbas was a major element of pre-war policy in the near east. Cox considered peace the priority, in the maintenance of good relations with the Ottomans, who held all the tribal loyalties, whilst prompting India to change policy towards Ibn Saud, the Wahhabi ruler of Nejd and later king of Saudi Arabia, from 1906^{[citation needed]}.

One of the few allies was Shaikh Mubarak of Kuwait, whose shared intelligence eventually aided the desert war. Cox was assiduous with his briefs: he prepared in great detail, in fluent Arabic, when he wrote Shaikhs. Warned by the former ambassador to Constantinople of Turkish escalation; preparations were made to make Arabian friends. British forces were called into Bushehr in 1909, and then again to Shiraz in 1911. Cox promised Sheikh Khazal of Muhammarah that troops would protect when the Turks threatened to invade. Khazaal leased the Shatt al-Arab waterway on the Euphrates to the Anglo-Persian Oil Company for the construction of refineries. In 1910 Cox wrote a full report on Shakespear's findings to India, which was passed to London. He was promoted to Lieutenant-colonel in February 1910. Cox promoted trade in the Persian Gulf which doubled between 1904 and 1914, suppressed the illegal arms trade; and improved communications. In 1911 he was created a Knight Commander of the Order of the British Empire. In 1908 oil fields were discovered in the region of Abadan. On 16 July 1909, after secret negotiation with Cox, assisted by Arnold Wilson, Sheik Khaz'al agreed to a rental agreement for the island including Abadan.

He was confirmed as Resident, a post which he occupied highly successfully until 1914, when he was appointed Secretary to the British Raj. Cox feared reprisals in Arabia would make the tribes turn towards Germany. But the Foreign Office was engrossed with events in Europe. Among his other achievements while at Bushire was the establishment of the state of Kuwait as an autonomous kaza within the Ottoman Empire by the Anglo-Ottoman Convention of 1913, where he improved relations with local ruler, Mubarak, by opening negotiations with Ibn Saud.^{[citation needed]}