Sienn'rha was a Twi'lek slave girl kidnapped by Bib Fortuna along with her friend Oola and trained to be a dancer for Jabba Desilijic Tiure. While being transported to Jabba's Palace, Jerris Rudd hid both girls that later were discovered by Luke Skywalker. Luke tried to help them both to escape, but Oola was suspicious. Rudd came and a fight began. Luke deflected all bolts from Rudd's blaster and killed him, providing the dancers a chance to escape. Oola then distracted the recently arrived Fortuna and urged Sienn to flee, naively thinking to thus ensure Jabba's patronage for only herself. Sienn later joined the Rebel Alliance.
During Rogue Squadron's mission to Ryloth to obtain Ryll kor, Sienn'rha was one of the dancers who entertained the pilots. She passed a message to Wedge Antilles that she would entertain him with a private dance if he wished, an offer he politely declined. This led her to silently question his sexuality.
Sienn was a name commonly attributed to Twi'lek females, and meant maiden in the Twi'leki language.