Batman: Arkham - Ranking EVERY Villain Worst To Best

Like looking at a shark in an aquarium, it's not what this man can do right now that unnerves you. Rather, it's what he did in the past - and what he'll do again if he ever gets out.

Calendar Man's main appearance is in Arkham City, locked in a cell below the Solomon Wayne Courthouse. A serial killer by the name of Julian Day, he is obsessed with dates and times, planning gruesome themed murders on specific holidays throughout the year.

He sits idly chanting the '30 Days Hath September' mnemonic until Batman approaches, and, depending on the time of the year, tells a story of one of his past holiday killings. It's only when he's told all he has to tell that he shares his final secret with the Dark Knight before escaping off-screen: "I was there at the beginning, and I will be there at your end."

And he's a man of his word, alright. During the Knightfall Protocol of Arkham Knight, Calendar Man can be seen among the crowd outside Wayne Manor, right before the building is blown to pieces. A truly disturbed man - but an honest one, at least.