The Theater an der Wien is a historic theatre in Vienna located on the Left Wienzeile in the Mariahilf district. Completed in 1801, the theatre has hosted the premieres of many celebrated works of theatre, opera, and symphonic music. Since 2006, it has served primarily as an opera house, hosting its own company.

The theatre was the brainchild of the Viennese theatrical impresario Emanuel Schikaneder. Schikaneder's troupe had already been successfully performing for several years in Vienna in the smaller Theater auf der Wiedenand this is where Die Zauberflöte had premiered. As the troupe's performances often emphasized spectacle and scenery, the librettist felt ready to move to a larger and better equipped venue. He had already been granted an imperial licence to build a new theatre in 1786, but it was only in 1798 that he felt ready to act on this authorization. The building was designed by the architect Franz Jäger in Empire style (it has since been remodeled). Construction was completed in 1801. The theatre opened on 13 June 1801 with a prologue written by Schikaneder followed by a performance of the opera Alexander by Franz Teyber. 

In 1807 the theatre was acquired by a group of court nobles that included Count Ferdinand Palffy von Erdöd, who bought it outright in 1813. During the period of his proprietorship, which lasted until 1826, he offered opera and ballet and, to appeal to a wider Viennese audience, popular pantomime and variety acts, losing money in elaborate spectacles until finally he was forced to sell the theatre at auction in 1826.

Only a part of the original building is preserved: the Papagenotor (Papageno Gate) is a memorial to Schikaneder, who is depicted playing the role of Papageno in Die Zauberflöte, a role he wrote for himself to perform. He is accompanied by the Three Boys, characters in the same opera.

The Theater an der Wien has seen the premieres of many works by celebrated composers and playwrights, among which are: : Fidelio, Beethoven’s 2nd , 3rd, 5th and 6th Symphony, Die Fledermaus, Die Lustige Krieg, Der Zigeunerbaron, Die Lustige Witwe, Der Graf von Luxemburg, etc. 

The theatre experienced a golden age during the flourishing of Viennese operetta, as referenced in the latter items in the above list of premieres.

From 1945 to 1955, it was one of the temporary homes of the Vienna State Opera, whose own building had been destroyed by Allied bombing during World War II. However, in 1955, the theatre was closed for safety reasons. It languished unused for several years, and by the early 1960s, the threat had emerged that it would be converted to a parking garage.

Fortunately, in 1962 the theatre found a new and successful role for itself as a venue for contemporary musical theatre. Many English-language musicals had their German premieres there. In 1992, the musical Elisabeth (about Franz Joseph I of Austria's wife, Elisabeth of Bavaria, also known as Sissi), premiered there. 

In 2006, the 250th anniversary year of Mozart's birth, the Theater an der Wien presented a series of major Mozart operas, thus initiating its conversion to a full-time venue for opera and other forms of classical music.