Āghā Moḥammad Khān Qājār (1742–1797)‎ is the founder of the Qajar dynasty of Iran, ruling from 1789 to 1797 as king (shah).

He is originally chieftain of the Qoyunlu branch of the Qajar tribe.

In 1789, Agha Mohammad Khan is enthroned as the king of Iran, but is not officially crowned as its king until March 1796.

On 17, June 1797 Agha Mohammad Khan is assassinated, and is succeeded by his nephew, Fath-Ali Shah Qajar.

Agha Mohammad Khan's reign is noted for the reemergence of a centrally led and united Iran.

Following the death of Nader Shah in 1747, many of the Iranian territories in the Caucasus that had been ruled by the various subsequent Iranian dynasties since 1501, today comprising Georgia, Dagestan, Azerbaijan, and Armenia, had broken apart into various Caucasian khanates or had declared de facto independence, as in Georgia's case.

After forty-eight years, they are all reconquered by Agha Mohammad Khan.

Some of his reconquests are, even for their time, exceptionally cruel, such as his re-subjugation of Georgia, where he sacks the capital Tblisi, massacres many of its inhabitants, and moves some fifteen thousand Georgian captives back to Iran.

Agha Mohammad Khan is also noted for moving the capital to Iranian Tehran, where it still stands as of today.