Based on their findings, these are the horror movies most likely to get viewers' hearts racing. To compile their list of the most terrifying horror flicks, GIGACalculator.com showed movies to 150 first-time viewers while tracking their heart rates. Taking the number 2 spot was the 2004 gore-fest Saw, which jacked up heart rates to an average of 113 BPM. As horror fans know, a movie that raises your heart rate in the moment won't necessarily give you nightmares days later. For another perspective on the best scary movies, check out the favorite horror films of famous directors in the genre.