A Life for the Tsar (Russian: Жизнь за царя, romanized: Zhizn za tsarya listen^ⓘ) is a "patriotic-heroic tragic" opera in four acts with an epilogue by Mikhail Glinka. During the Soviet era the opera was known under the name Ivan Susanin (Russian: Иван Сусанин listen^ⓘ), due to the anti-monarchist censorship.

The original Russian libretto, based on historical events, was written by Nestor Kukolnik, Egor Fyodorovich (von) Rozen, Vladimir Sollogub and Vasily Zhukovsky. It premiered on 27 November 1836 OS (9 December NS) at the Bolshoi Kamenny Theatre in Saint Petersburg. The historical basis of the plot involves Ivan Susanin, a patriotic hero of the early 17th century who died in the expulsion of the invading Polish army for the newly elected Tsar Michael of Russia, the first of the Romanov dynasty, elected in 1613.

The plot of A Life for the Tsar had been used earlier in 1815, when Catterino Cavos, an Italian-Russian composer, had written a two-act singspiel with the same subject and title. The original title of the opera was to be Ivan Susanin, after the hero, but when Nicholas I attended a rehearsal, Glinka changed the title to A Life for the Tsar as an ingratiating gesture. This title was retained in the Russian Empire.

In 1924, under the new Soviet administration, it appeared under the title Hammer and Sickle, but that production was not successful and was shelved. On 26 February 1939 it reappeared under the title Glinka had originally chosen, Ivan Susanin.

Glinka and the writers with whom he was associated chose, in Susanin, a hero of Russian nationalism well suited to the mood of the time. The opera was immediately hailed as a great success, and became the obligatory season-opener in the Imperial Russian opera theaters. A Life for the Tsar occupies an important position in Russian musical theater as the first native opera to win a permanent place in the repertoire. It was one of the first Russian operas to be known outside Russia.

The opera was given its premiere performance on 27 November 1836 in Saint Petersburg conducted by Catterino Cavos with set designs by Andreas Roller. It was followed several years later with its premiere in Moscow on 7 September (Old Style) 1842 in a new production with sets by Serkov and Shenyan.

Glinka's opera was featured heavily throughout the Romanov Tercentenary celebrations in 1913. It was performed in a gala performance at the Mariinsky Theatre, Schools, regiments, and amateur companies throughout imperial Russia staged performances of A Life for the Tsar. Pamphlets and the penny press printed the story of Susanin "ad nauseam", and one newspaper told how Susanin had shown each and every soldier how to fulfill his oath to the sovereign. The image of the seventeenth-century peasant features prominently at the bottom of the Romanov Monument in Kostroma, where a female personification of Russia gives blessings to a kneeling Susanin. In Kostroma, Tsar Nicholas II was even presented with a group of Potemkin peasants who claimed to be descendants of Susanin.

In keeping with Glinka's European training, much of A Life for the Tsar was structured according to conventional Italian and French models of the period. Nevertheless, several passages in the opera are based on Russian folk songs or folk melodic idioms that become a full part of the musical texture.