What was the first zombie movie?

Let me ask you a question: Are you one of those people who starts posting memes about fall as soon as it hits September? Do you watch a different scary movie every day in October, culminating in that one perfect horror movie you watch every year on Halloween night? Do you make Jell-O brains for dessert just for fun?

If you answered yes to any of those questions, you've probably seen at least one zombie movie in your life.

It's a rich and storied legacy that also spawned the TV zombie craze, which apparently is still going. Daryl from The Walking Dead will eventually just find an old folks home that has somehow been totally untouched by the zombie plague and call it good. And then it will turn into a romantic-comedy sitcom about Daryl and the orderlies and how he sometimes still has to go kill zombies. And probably Carol is there somehow.

But I digress... all of this undead mania has its roots, arguably, in a single film. Of all the masters who have touched this genre, only one could have started it all.

What production marked the first known zombie movie in cinema history?