Star Butterfly, also known as Star the Underestimated, is the main and titular protagonist of Star vs. the Forces of Evil. She is a teenage princess of the Kingdom of Mewni (located in another dimension) sent to Earth by her parents in order to learn how to use the royal magic wand, with supervision from Glossaryck.

In seasons 1-2, she lives with her Earth hosts, the Diaz family. In season 3, she returns home to Mewni. As of season 4, she lives in the Monster Temple following the destruction of Butterfly Castle. She was also the 37th Queen of Mewni for four days^[​11] before giving the kingdom back to Eclipsa Butterfly.^[​44] As of "Doop-Doop", she is back to living on Earth. From "Here to Help" onward, she is Marco's girlfriend.