The heroes of Left 4 Dead 2—Coach, Ellis, Rochelle, and Nick—have traveled back to World War 2 to join the cast of a different four-player zombie shooter, Zombie Army 4. They're available in a free DLC called the Left 4 Dead Character Pack 2 (opens in new tab), which follows similar free DLC from a couple of months ago that added the original game's heroes, Left 4 Dead Character Pack 1 (opens in new tab).
They don't come with character voices unfortunately, so you won't be able to hear Ellis ramble his good-old-boy stories as you blast Nazi zombies, but it's a fun freebie nonetheless. Zombie Army 4 also has some paid DLC out this month, like Return to Hell (opens in new tab), the conclusion of a story that's played out across previous episodic DLC. As the name suggests, it sends you to Hell, where you'll face enemies including some real creepy mannequins.
There's also some new packs adding Van Helsing Weapon Skins (opens in new tab), a Flare Gun Weapon Bundle (opens in new tab), the Horror Charm Pack 2 (opens in new tab), and Horror Headgear (opens in new tab) if you really want to wear a sack or dollface mask while shooting zombies in Hell. All of the above is also bundled together in Season Pass Three (opens in new tab).