Comet the Super-Horse, from the Superman comics
Creepy Because: Bestiality.
Comet is Supergirl's pet horse. At first this sounds really cute, because girls love horses. Although, there is this book we once read in the Cracked offices called The Naked Ape that teaches us that girls like horses because riding them is the closest activity to non-threatening sex they can have. Not so cute anymore? Yeah, wait until you read how creepy it becomes with a stalker Super-Horse involved.
You see, according to the comic, Comet was once a centaur called Biron back in ancient Greece. He was turned into a full horse by a witch, though as a small consolation, he gained superpowers and kept his humongous horse penis.
Also, Comet periodically turns into a full human, at which point he does what any horse would do: Try to get laid with Supergirl before she can figure out he is really her horse.
You see, the horse is in love with the girl who, while he's in horse mode, dry humps his back as a means of transport. Comet never makes his feelings known and thus allows this arrangement to continue, much like those "nice guys" who orbit around a girl every day doing her favors, while complaining endlessly in their LiveJournals because the girl doesn't pay back their niceness with a blowjob.
That's right, Comet! The court's orders are meaningless!
And to make the whole thing even more unsettling, he is a super-horse, which zoologists tell us adds at least six inches in length and one in girth.
Ultimate Quicksilver and Scarlet Witch from The Ultimates
Creepy Because: Twincest.
The Ultimates is a modernized, alternate universe version of The Avengers where they finally figure out they are not really avenging anybody or anything in particular and that the name Defenders was already taken. Quicksilver and the Scarlet Witch are the twin son and daughter of Magneto. Just by taking a second look at that picture up there, unless you are a relative of that banjo playing kid from Deliverance, you can start guessing what their problem is.
Yes, both kids have decided to keep it in the family, and when we mean "it" we mean Quicksilver's penis, and when we mean "the family" we mean "his sister's vagina." In the beginning of the series, the incest was subtly implied and kept as a joke of something that happened off panel and could easily be denied, until the third series came around and we got this.