Teatre Principal, Art Nouveau theater in Terrassa, Spain.

Teatre Principal stands at plaça de Maragall 2, its eclectic facade crowned by a dome covered in mosaics. The main front keeps polychrome stained glass with plant motifs and the busts of actor Joan Prat i Ubach and composer Emili Daura i Oller, survivors of Pau Gargallo's sculptures. The 2007-2011 remodelling by Xavier Fabré and Lluís Dilmé left 623 seats between stalls and amphitheatre, plus about a hundred more in the Sala de la Cúpula.

The theatre's origins date to 1866, when it served the city's industrial bourgeoisie. The present building, remodelled by Enric Catà and Francesc Guàrdia, opened on 15 December 1911 with the operetta La Geisha. In 1916 Josep Maria Coll i Bacardí removed the Modernista decoration from the facade. The city bought the building on 10 November 2005 and reopened it on 24 March 2011 after works by Xavier Fabré and Lluís Dilmé.

Two portrait busts honor the artist Joan Prat i Ubach and the composer Emili Daura i Oller, both from Terrassa. These sculptures celebrate local figures who shaped the city's artistic identity.

The theatre stands at Plaça de Maragall 2, in the centre of Terrassa. After the 2007–2011 remodelling by architects Xavier Fabré and Lluís Dilmé it holds 623 seats in the stalls and amphitheatre, plus about a hundred more in the Sala de la Cúpula. The main entrance is on the square; the building is a protected historic-artistic asset, so access to the auditorium depends on the performance schedule.

On 29 March 1914 Enric Granados played a concert here and premiered an improvisation on the theme of his piece El pelele, which had not yet been performed; its definitive version only appeared in March 1915 at the Palau de la Música Catalana. On 1 January 1926 the Argentine tango singer Carlos Gardel performed in the theatre during his tour of Spain.