Samantha Grimm

Samantha Grimm, a character in the Doom motion picture, is a scientist working on Mars at the Olduvai Research Facility. She is the twin sister of John Grimm (Reaper), who is the story's main protagonist and a member of the Rapid Response Tactical Squad. She becomes one of the first (and the few) characters at the facility to understand what is taking place.

Story
After the RRTS finds Dr. Carmack, whose blood cannot be identified, she starts an autopsy on the mutated Dr. Willits. Through this examination, she realizes that the creatures attacking are human.

Later in the film, her brother is mortally injured. With the only other option being to watch him die, she chooses to inject him with the experimental 24th chromosome. Instead of being mutated into a monster like the other victims, Reaper instead gains superhuman strength, speed, and agility, and uses those traits to clear a path for the two of them to the base's exit. Samantha is last seen barely clinging to consciousness in her brother's arms as they ascend to the surface of Earth.