Alissa Vincent (voiced by Nika Futterman) is the main protagonist of the animated feature Dead Space: Downfall. She was the head of security aboard the USG Ishimura, a Planet-Cracker class starship contracted by the Church of Unitology to extract an alien relic known as the Marker from the planet Aegis VII. When the Marker was brought aboard, violence ensued as numerous crew members began to go insane, murdering fellow crewmates or committing suicide and then being transformed into horrific undead monstrosities known as Necromorphs.
Alissa and her security team struggle valiantly to fight off the Necromorphs infesting the Ishimura and save the crew. The team's struggle proved to be in vain as many of them succumbed to the influence of the Marker, losing their sanity and turning violent. Soon, Alissa found herself alone as her entire team was killed, deciding to deploy a message beacon into space to alert other ships of the Ishimura's fate and urge them to destroy the doomed ship and the Marker. With all of the ship's escape shuttles having been launched into space by the Necromorphs to stop the crew from fleeing, Alissa was forced to open the hangar doors and hold on for dear life as the beacon was vented into space. Alissa attempted to get inside a wrecked shuttle, that ironically had originally brought the necromorphs, in the hangar, but could not hold on as the decompression blew her out into space as well.