What fans of "The Walking Dead" universe already know everyone is infected. When someone dies, they turn into a "Walker."

But what they don't know is who was the first to turn. Who was the first to start the apocalypse? According to Comic Book, that person's name is Gloria and she will be played by actress Lexi Johnson.

In that very first trailer, fans saw Nick Clark (Frank Dillane) running from a building. As it turns out, this scene was immediately following the very first encounter anyone in the world had with a zombie. Clark was running from Gloria, Patient Zero, who was chowing down on a man's face.

When the first trailer was released, fans didn't know that was the point in time that officially started the Walker Apocalypse.

Johnson revealed in an interview with Comic Book that she had an audition for the part, but it wasn't for just any zombie.

"In full make-up, they gave me full wardrobe, they dowsed me in blood with the contacts, they turned on the camcorder, and they were like, 'Alright, start walking. Start pretending like you're eating someone,'" Johnson said.

For her, it was like a dream role. A chance to be on a series that she was already a huge fan of.

"It's really surreal. It really hasn't hit me yet. I'm actually a giant fan of the original show," Johnson told Comic Book. "A couple months before I landed the role of Gloria, I was just sitting there saying, 'How amazing would it be just to be one of the zombies on the show?' And then a couple months later the opportunity came and I booked it!"

Although it is unclear at this point where in the timeline this will happen, producers and showrunners have given a vague timeline of the two-month period that Rick Grimes was in a coma on "The Walking Dead."

Check out the interview below.