Billy (also known as Billy the Doll) is one of the sub-icons featured at the Halloween Horror Nights: Ripped from the Silver Screen event at Universal Studios Florida, and is also the main icon at the Halloween Horror Nights 2009 event at Universal Studios Hollywood. He has been featured in all seven Saw movies.
In the films Saw, Saw II and Saw III, Bily is built by Jigsaw Killer, and is used to communicate with Jigsaw's victims on how to survive his gory traps. Following Jigsaw's death in Saw III, Billy is instead used by Mark Hoffman, Jigsaw's follower, in Saw IV, Saw V and Saw VI for communicating with victims. In Saw 3D: The Final Chapter, he is used by Doctor Gordon and Hoffman.
In Saw, Saw II and Saw III, Billy is voiced by Tobin Bell. In Saw VI, Saw V, and Saw VI he is voiced by Costas Mandylor. In Saw 3D: The Final Chapter, he is voiced by Costas Madylor, and Cary Elwes.