[This article includes SPOILERS for Batman V Superman: Dawn of Justice.]
Does Batman kill? Yes. He does. But depending on the version of the character being talking about, he may be more or less cavalier about it. The Dark Knight trilogy, the second most recent film adaptation of Batman, presented "no killing" as a hard and fast rule -- except for situations where he could find a loophole, like inaction, to allow a death. Or, in more severe cases, the fire-that-killed-all-the-ninjas scenario.
The interesting thing about the debate is that it seems more driven by an occasionally acknowledged moral policy than the reality of most modern superheroics. Most heroes kill nowadays, and most fans accept that, but that didn't stop criticisms being leveled against Batman's attitude toward killing in his most recent film, Zack Snyder's Batman V Superman: Dawn of Justice.
As you might expect, to address the issue, YouTube personality Mr. Sunday released another video in his Kill Count series. He had highlighted Batman before, but this time his video (above) focuses solely on Ben Affleck's iteration of the Dark Knight in BvS. Battfleck's final tally comes to 21, but he dreams about killing even more.
Many of these kills can be seen as justifiable, especially in the rescue of Martha sequence (protecting the innocent from her captors), and in the Knightmare sequence (clear case of self defense). But seeing Batman dispassionately crush and shoot LexCorp security personnel in the Batmobile because they're between him and something he wants (kryptonite to kill Superman), seems like an awfully supervillainish thing to do. It's possible, even likely, that these men were amoral mercenaries, but this never being established, it puts Batman in the awkward position of having possibly murdered innocents for what he sees as the "greater good." Considering Batman is the ultimate ninja superhero, it's especially surprising that "sneak in, steal the kryptonite, sneak out" wasn't his first course of action.
While BvS is often compared to Captain America: Civil War, Marvel's hero vs. hero counterpart this year, another MCU entry seems like a more apt comparison for this particular issue: season 2 of Marvel's Daredevil, released on Netflix just before BvS hit theaters. A large chunk of the season was spent comparing both Punisher and Elektra's "take no prisoners" attitude to Daredevil's "no deaths on my watch" policy. Superhero comics and movies are obviously a form of escapism, and as such, cannot be taken as literal examples of human "goodness." But with vigilantism already putting larger-than-life heroes on questionable moral ground, it helps to at least have a discussion about the responsibility they hold over life and death, especially when death is featured so prominently.
Batman V Superman: Dawn of Justice and its Ultimate Edition are now both available digitally, with DVD and Blu-ray releases coming July 19, 2016.