When it comes to horror comics, there are comics that unsettle and comics that disturb, and there are those that just fail to do anything other than ellicit a shrug and a yawn and make you want to read something else. But there's only ever been one comic that's stuck with me as actually scary, even though it really shouldn't have been the case, and that's The Thirteenth Floor.
The Thirteenth Floor was a fairly long-lived British strip - it survived the cancellation of its original home, which either speaks to the possibility that the strip had similar responses from other readers, or that nothing else was really happening at the time - that came from the minds of John Wagner and Alan Grant (writing under a pen name), in full-on "stealing ideas and making them palatable for kids' comics" mode (It wasn't a 2000AD strip, but instead got started in 1984's Scream, a horror comic from the same publishers). Really, what made the ten-year-old me scared of the strip wasn't actually the story itself, but the backstory to it. I'll explain.
2001: A Space Odyssey was a very scary film for me, as a child. It's not the whole psychedelic rebirth-of-the-species ending that freaked me out - That just bored me to death - but HAL. HAL was terrifying to me, when I was young; the idea that a computer could go slightly... off... and suddenly become this dangerous, deadly machine without even really being aware of it - and that he could be like that while still having this calm, friendly "I can't allow you to do that, Dave" voice - was the scariest thing in the world to me. So, when Wagner and Grant stole that idea and made it the central idea of The Thirteenth Floor, I wasn't just dealing with the comic itself, but all my HAL baggage, too.
The idea behind The Thirteenth Floor was a simple one: There was an apartment building that had been fitted with Max, an experimental AI that ran everything, and loved its tenants. Loved them, in fact, so much that anyone who it believed would upset them had to be dealt with, which happened thanks to some holographic technology and a mysteriously non-existent 13th floor. When put like that, it seems kind of cliched, but I didn't feel like that at the time. Instead, I completely bought into the idea, and it really made me nervous. It wasn't that the punishments potential evildoers were dealt out were the scary thing, but the idea that, somewhere, there really might be a Max, just waiting for the ability to announce his presence to the world and start offering up his own brand of pre-emptive justice.
What tends to leave me cold about most horror comics - and horror movies, for that matter - is an over-reliance on gore and shock and doing the visual equivalent of shouting BOO in your face. Even when I was 10, that didn't really scare me, but computers that think for themselves and can create their own worlds to sweetly try and make your life better through really, really bad actions? Even twenty-six years later, that kind of thing makes me want to hide under the covers, just because I'm still semi-convinced it's just around the corner.
(For the curious, the long out-of-print original strips can be read here. You'll be able to see for yourself just how much of a wuss I actually am.)