File this under "gone too soon". Ms. Murphy appeared in films like "Clueless", "8 Mile" (w/Eminem), and "Just Married", and lent her voice to Luanne on the recently concluded Fox series, King of the Hill. She passed away earlier today reportedly due to cardiac arrest. There is already speculation that drugs were involved, but nothing at this writing can be confirmed to that end.
Ms. Murphy's only other voice work of note was in the movie "Happy Feet", for which she also recorded two songs for the soundtrack. Her next film will be the thriller, "The Expendables", due in the spring of 2010, and was reportedly working on a film with Nicole Kidman at the time of her passing.
Rest in peace, Brittany. You will be missed.