| Viola | |
| Genre Header: | Opera |
| Composer: | Bedřich Smetana |
| Image Upright: | 0.9 |
| Librettist: | Eliška Krásnohorská |
| Language: | Czech |
| Based On: | Shakespeare's play Twelfth Night |
| Premiere Location: | National Theatre, Prague |
Viola is an unfinished romantic opera by Bedřich Smetana. The libretto was written by Eliška Krásnohorská, and is based on Shakespeare's play Twelfth Night. The composer did some work on it in 1874 and then came back to it in 1883, when he only managed to orchestrate a few scenes; the opera was left incomplete upon Smetana's death in 1884.
A concert performance (of the unfinished work) was given on 15 March 1900 and it was staged at the Prague National Theatre on 11 May 1924.
| Orsino, Duke of Illyria | tenor |
| Viola, twin sister to Sebastian | mezzo-soprano |
| Sebastian, twin brother to Viola | soprano |
| Olivie | mezzo-soprano |
| Tobiáš | baritone |
| Ondřej | tenor |
| Malvolio | baritone |
| Marie | soprano |
| Šašek | baritone |
| Antonio, a captain | bass |
| Marko, an old fisherman | bass |