The Alien is portrayed by both Woodruff Jr. in a suit and a rod puppet filmed against bluescreen and optically composited into the live-action footage, with the rods removed by rotoscoping. A mechanical alien head was also used for close-ups. The suit adapted the design used in "Aliens" so Woodruff could walk on all fours. Woodruff's head was contained in the neck of the suit, because the head was filled with animatronics to move the mouth of the Alien. Fincher suggested that a Whippet be dressed in an alien costume for on-set coverage of the quadrupedal alien, but the visual effects team was dissatisfied with the comical result and the idea was dropped in favor of the puppet.