If you've watched a horror film in the past 30 years, there's a good chance Greg Nicotero is the man behind its goriest scenes.
He's produced prosthetic effects for hundreds of movies including Pulp Fiction, Hostel, Kill Bill and Sin City.
Greg's also an integral part of TV show The Walking Dead - working as a producer, director and, of course, make-up artist.
Here's his guide to the fine art of splattering blood on screen.
"It's almost like a magic trick," he tells Newsbeat. "We're using misdirection, we're using slight of hand and different things."
He's describing the moments of extreme gore he's known for - a limb being pulled off, or a zombie being crushed to death - which he calls "gags".
"It's all about the impact that they have and in many instances it's about the impact that particular moment has on the character in the scene.
"So when you see something happen on The Walking Dead - and then we cut to a character's reaction - people very often react to how a character's reacting rather than the thing they've seen."
Greg's team creates practical effects - that means they're achieved largely through make-up and other techniques in the 'real world', rather than digital effects added after filming.
Those practical effects make for some interesting behind-the-scenes photos of extras.
When he started out in the 1980s, Greg worked under George A Romero - the man behind classic zombie movies like Night of the Living Dead (1968) and Dawn of the Dead (1978), reports BBC.
Those films have influenced modern zombie movies and TV shows including Shaun of the Dead and The Walking Dead.
Despite the huge progress made in digital effects and CGI (computer generated imagery) during his career, for a large part Greg has stuck to the practical prosthetic make-up techniques in which he made his trade.
But he says he's not completely stuck in his ways.
