The theremin repertoire is quite large. In earlier times, there was a belief that the theremin was only suitable for lyrical, slow melodies or spooky, sci-fi, and psychedelic effects. However, this myth was refuted long ago. The pieces you can play are those you can work out musically. It depends on your musical taste and experience.
The theremin is used in classical, contemporary, jazz, and popular music, as well as in different kinds of experimental art.
See below the link to most popular works played on the theremin, with the links to the recordings.