There are two bands/artists with this name:
1. An American model, R&B singer, and occasional actress
2. A Finnish dream-pop/shoegaze/post-rock band : http://cassie.bandcamp.com/
1. Cassandra Ventura (born on August 26, 1986) is an American model, R&B singer, and occasional actress. She is best known for her single Me & U, which became a hit in the summer of 2006.
Cassie was born in New London, Connecticut, United States and moved to New York City and continued modeling; she attended classes at the Broadway Dance Center. Read more on Last.fm