William O'Brien is an American animator, artist and video game producer. He is also a current employee of Bungie Studios. Born and raised in Boston, Massachusetts, USA, he attended art school and majored in animation. He specializes in both 2D and 3D animation.
He was credited as one of the animators for Halo 2.
- O'Brien had an ODST don his name in the short, Another Day at the Beach. His ODST character died in a Pelican crash during the events.