Abbas the Great or Abbas I of Persia (Persian: شاه عباس بزرگ; 27 January 1571 – 19 January 1629) was the 5th Safavid Shah (king) of Iran, and is generally considered one of the greatest rulers of Iranian history and the Safavid dynasty. He was the third son of Shah Mohammad Khodabanda.Although Abbas would preside over the apex of Iran's military, political and economic power, he came to the throne during a troubled time for the Safavid Empire. Under his ineffective father, the country was riven with discord between the different factions of the Qizilbash army, who killed Abbas' mother and elder brother. Meanwhile, Iran's enemies, the Ottoman Empire (its archrival) and the Uzbeks, exploited this political chaos to seize territory for themselves. In 1588, one of the Qizilbash leaders, Murshid Qoli Khan, overthrew Shah Mohammed in a coup and placed the 16-year-old Abbas on the throne. However, Abbas soon seized power for himself.

Under his leadership, Iran developed the ghilman system where thousands of Circassian, Georgian, and Armenian slave-soldiers joined the civil administration and the military. With the help of these newly created layers in Iranian society (initiated by his predecessors but significantly expanded during his rule), Abbas managed to eclipse the power of the Qizilbash in the civil administration, the royal house, and the military. These actions, as well as his reforms of the Iranian army, enabled him to fight the Ottomans and Uzbeks and reconquer Iran's lost provinces, including Kakheti whose people he subjected to widescale massacres and deportations. By the end of the 1603–1618 Ottoman War, Abbas had regained possession over Transcaucasia and Dagestan, as well as swaths of Eastern Anatolia and Mesopotamia. He also took back land from the Portuguese and the Mughals and expanded Iranian rule and influence in the North Caucasus, beyond the traditional territories of Dagestan.

Abbas was a great builder and moved his kingdom's capital from Qazvin to Isfahan, making the city the pinnacle of Safavid architecture. In his later years, following a court intrigue involving several leading Circassians, Abbas became suspicious of his own sons and had them killed or blinded.