Ivan Alexander (Bulgarian: Иван Александър, transliterated Ivan Aleksandǎr, pronounced [iˈvan ɐlɛkˈsandɐr]; original spelling: ІѠАНЪ АЛЄѮАН^дРЪ), also sometimes anglicized as John Alexander, ruled as Emperor (Tsar) of Bulgaria from 1331 to 1371, during the Second Bulgarian Empire. The date of his birth is unknown. He died on 17 February 1371.

The long reign of Ivan Alexander is considered a transitional period in Bulgarian medieval history. Ivan Alexander began his rule by dealing with internal problems and external threats from Bulgaria's neighbours, the Byzantine Empire and Serbia, as well as leading his empire into a period of economic recovery and cultural and religious renaissance.

However, the emperor was later unable to cope with the mounting incursions of Ottoman forces, Hungarian invasions from the northwest and the Black Death. In an ill-fated attempt to combat these problems, he divided the country between his two sons, thus forcing it to face the imminent Ottoman conquest weakened and divided.

Ivan Alexander was the son of the Despot Sracimir of Kran by Petrica, a sister of Michael Asen III of Bulgaria. Therefore, Ivan Alexander was a nephew of Michael Asen III. Paternally, Ivan Alexander descended from the Asen dynasty. By 1330 Ivan Alexander was a despot and governed the city of Lovech. Together with his father and his father-in-law Basarab of Wallachia, Ivan Alexander fought in the Battle of Velbazhd against the Serbs at modern-day Kyustendil in 1330, in which Bulgaria suffered a defeat. The defeat, combined with the worsening relations with the Byzantine Empire, precipitated an internal crisis, which was exacerbated by an invasion of the Byzantines. A coup d'état drove Ivan Stefan out of the capital Tarnovo in 1331, and the conspirators placed Ivan Alexander on the throne.

The new ruler set about consolidating his position by regaining territories recently lost to the Byzantine Empire. In 1331 Ivan Alexander campaigned around Adrianople and reconquered northeastern Thrace. Meanwhile, Stefan Uroš IV Dušan deposed his father Stefan Uroš III Dečanski and became Serbian king in 1331. This helped normalize the previously tense relations between the two countries. Ivan Alexander and Stefan Uroš IV Dušan concluded an alliance, which was cemented by the marriage of the Serbian king to Helena of Bulgaria, a sister of Ivan Alexander, on Easter 1332.

At about the same time, Belaur, a brother of Michael Asen III, rebelled in Vidin, probably in support of his deposed nephew Ivan Stefan's claim to the throne. The advance of the Byzantine Emperor Andronikos III Palaiologos against Bulgaria in the summer of 1332 protracted military operations against the rebels. The Byzantines overran Bulgarian-controlled northeastern Thrace, but Ivan Alexander rushed southward with a small army and swiftly caught up with Andronikos III at Rusokastro.

Nobody of our first tsars seems to us like this great tsar Ivan Alexander, in his military power he looks to us like a second ancient Alexander the Great, in faith and piety he is a second Saint Constantine; he captured thus all his enemies, put them under his knees and established firm peace in the Universe.

— Praise to Ivan Alexander by an anonymous contemporary of the tsar