David Warren "Dave" Ellefson (born November 12, 1964) is a bassist and founding member of the American thrash metal band Megadeth. He has also been referred to as "Junior" to differentiate him from Dave Mustaine. Ellefson currently resides in Scottsdale, Arizona. In addition to playing bass guitar in Megadeth, Ellefson also has various side projects which include Temple of Brutality, F5, and Killing Machine.