- ❝ For the last time I'm sorry, Debbie. Come on, I know it's June-ish. ❞
- — Calendar Man
Julian Day, primarily known as Calendar Man, is a supervillain obsessed with committing crimes on holidays and specific dates, but he just can't remember his own son's birthday. However, despite this, he’s getting there because he remembers that it’s June-ish.
He was an inmate at Arkham Asylum with Harley Quinn and Poison Ivy before Ivy staged an escape. While incarcerated alongside them, he kept track of how many days Harley had been there which became a point of contention as he was visited by his wife and son and she became annoyed that he would remember that while forgetting his own son's birthday. He is later seen to have escaped and being a part of the Legion of Doom as he was present during the party at the Hall of Doom when Harley was nominated to join and Aquaman attacked.
- Calendar and Date-related Knowledge
- "All the Best Inmates Have Daddy Issues" (flashback; cameo)
Harley Quinn: Black + White + Red
- His head marked with calendar months are similar to the Batman: Arkham Asylum game series.
- This version of Calendar Man seems to combine the gimmicky costume version and the more serious serial killer version.