Hollywood’s biggest horror franchises have lately been lacking in all-star villainy. This isn’t to demonize long-running hit series such as The Conjuring, Insidious, and The Purge, none of which rely on one big bad guy. But many of scary cinema’s most infamous adversaries—Michael Myers, Leatherface, Freddy Krueger, Jason Voorhees—have grown quite long in the tooth, without any obvious contemporary heirs. Perhaps it’s fitting, then, that Saw X, one of the biggest horror-movie offerings this Halloween season, centers on a man in his early 80s. I refer to John Kramer (played by Tobin Bell), otherwise known as the Jigsaw Killer, an ornery civil engineer who’s obsessed with trapping people in escape rooms that are heavy on death and dismemberment. Jigsaw first popped up in Saw (2004), a tiny indie directed by James Wan that became a surprise smash, grossing $103 million worldwide on a $1.2 million budget. The franchise was quickly run into the ground off that success, pumping out a sequel every year until 2010’s risible Saw 3D. Since then, two halfhearted reboot attempts have …