To Everything (Turn Turn Turn) There is a Season
Calendar Man was created in 1958 by Bill Finger and Sheldon Moldoff. The character made seven appearances from 1958 to 1996. In 1996 Jeph Loeb and Tim Sale rewrote him for the Long Halloween where he played a major role in the murder mystery.
His real name is Julian Day. For most of his existence in the Batman mythos Calendar Man was essentially a gimmick character, committing larceny according to days of the week, holidays, and seasons. He morphed into a supervillain with super weapons used to pull heists, and then built elaborate traps to kidnap victims for ransom.
Loeb rewrote him as a Hannibal Lector type of character. This idea of him being a high functioning sociopath, a dangerous mastermind with an obsession with dates helped resurrect the character and save him from being forever a joke character, like Kite Man, the Polkadot Man, and Crazy Quilt. This version of Calendar Man was also used in the Batman Arkham games, which painted him as a very dangerous adversary, contrary to his long history of gimmicky nonsense. In those games Calendar Man is a serial killer who plans elaborate mass killings based around holidays.
Recently, Scott Snyder rewrote the character again, bringing in a supernatural element. Julian Day now lives, dies, and reincarnates according to seasons. Each time he dies, he then molts into a new Calendar Man. Apparently, each time he dies and is reborn, his personality changes.
Like many other classic Batman villains, Calendar Man has evolved from a silly crook obsessed with committing crimes based on calendar dates into a much darker psychotic mass murderer with creepy superpowers and possible immortality. However, the character just appears to mirror traits from other villains. The Joker creates mass murder events, the Riddler builds elaborate traps, the Mad Hatter kidnaps victims, Mr. Zsasz is a serial killer, even Alberto and Sofia Falcone murder people on holidays. Solomon Grundy dies and is reborn also, each time his personality changes.
Snyder hadn't given his new Calendar Man an origin. Now that his run on Batman is over, we will see if a new writer expands on this new take on the character. Despite the obvious borrowing from other villains, the calendar/seasonal/holiday theme is a good one, taking elements of time, cycles, and celebration and warping them into something to be feared. Calendar Man, like many other lame comicbook villains seems to have been redeemed and turned into something truly terrifying.