Nikki Sixx (born Frank Carlton Serafino Feranna Jr.; December 11, 1958) is an American musician, best known as the co-founder, bassist, and primary songwriter of the heavy metal band Mötley Crüe, being the only member to remain throughout their entire history.Prior to forming Mötley Crüe, he was a member of Sister before going on to form London with his Sister bandmate Lizzie Grey.