Hussein ibn Ali or Husayn ibn Ali (died 1931) was the Sherif of Mecca, and Emir of Mecca from 1908 until 1917, when he proclaimed himself king. He ruled until 1924, when he was defeated by Abdul Aziz al Saud.

Hussein ibn Ali was the last of the Hashemites to rule the Hejaz. Hashemite rule over the region had existed in unbroken succession since 1201. During World War I, Hussein was initially allied with the Ottomans and Germany, but was convinced by T. E. Lawrence ("Lawrence of Arabia") to rebel. Hussein was an important leader in the Arab Revolt against the Ottomans. Hussein allied himself with both France and the United Kingdom, and intended to form a unified Arab state that would stretch from Syria to Yemen.

In the aftermath of the war, the Arabs found themselves freed from the Ottomans but under the control of France and the United Kingdom. The sons of Hussein were made the kings of Jordan, Syria and Iraq. However, the monarchy in Syria was abruptly ended when the French were given control over the nation.

When Hussein declared himself king of the Hejaz, he also declared himself king of all Arabs. This brought him into conflict with Ibn Saud, and Saud defeated Hussein in 1924. He was then forced to flee to Cyprus. He went to live in Amman, Jordan, where his son Abdullah was king. Hussein died there in 1931. His son Faisal was made King of Iraq.