[Warning: Major spoilers from The Walking Dead comic book series are below. Seriously, stop reading if you do not want to be spoiled.]

Not all deaths are created equal in the world of The Walking Dead.

The 167th issue of Robert Kirkman's ongoing zombie comic may have just delivered one of the most upsetting deaths in the series.

While the writing had been on the wall for the past few issues, original character Andrea was killed off in this month's issue. As she battled the massive zombie horde amid an attack by the newly regrouped Saviors, Andrea sustained a zombie bite on her neck. After fighting on to protect Alexandria, she returned home to partner Rick, who immediately realized the placement of the bite meant certain death.

In the latest issue, Andrea was able to say goodbye to everyone - including Carl - and provide Rick with the encouragement he needed to go on leading the community after her death. After she passed, Rick was briefly unable to shoot Zombie Andrea and wound up stabbing his love in the face before meeting the rest of the community and stepping back into his role as a leader.

The issue marked the end of the road for one of the comic's original characters who, like Rick, Carl and Michonne, was considered untouchable. Fans of the AMC take on The Walking Dead will remember Laurie Holden's version of Andrea was shockingly killed off early - in the season three finale - with the actress recently revealing that she had an eight-year deal to remain on the series and, like her comic book character, become Rick's love interest. It's one of the AMC drama's biggest departures from Kirkman's source material that paved the way for the show's romantic pairing of Rick and Michonne.

Rather than featuring the monthly letters column as well as promos for forthcoming titles from Skybound, the issue ended with an emotional note to fans from Kirkman, in which he apologized for Andrea's death. Watch the video, below, to see how the issue plays out and scroll down to read Kirkman's letter.

I'm sorry. I'm sorry to my fans and to myself and to Andrea. I feel like I killed a close friend. The deaths in this series are never taken lightly, they're never done with a sense of glee. They weigh on me the same way they weigh on you. These characters are very real to me, and their deaths are upsetting even to me.

I plotted this issue out during a plane ride a few months ago. I plot my stories down with a pencil and paper, and there I was in my seat, blocking out scenes and writing dialogue surrounded by strangers who probably thought I was jotting down a shopping list. As I was writing some of the moments from this issue, I started crying. I found myself glancing around, wiping my eyes, hoping no one would notice. I've been living with this death for months now…and I don't like it.

I had plenty of time to change my mind. I had plenty of time to just not do it. I am in control of this story after all. But honestly, sometimes it feels like I'm not. This was one of those times. I don't like this. I don't want this. I want Andrea to live. I want to write more stories with her. I want to see her and Rick grow old together, watching Carl grow up and have kids of his own. I want that kind of happiness for these characters.

And yet, here we are.

Andrea is dead and the story moves on. I don't know why this had to happen…but I know it did. I know this is another important turning point in the life of this series. I know Andrea's death with mean something, that it will resonate in the stories moving forward for years to come. But I still don't like it. It still upsets me.

I loved Andrea and I will truly miss her.

- Robert Kirkman

Read more: 'Walking Dead': How Main Characters Die on the Show vs. the Comics

For more Walking Dead coverage, bookmark THR.com/WalkingDead.