The Season of Infamy is a Batman: Arkham Knight DLC released December 22, 2015. It includes 4 Missions with past villains: Mad Hatter (Jervis Tetch), Killer Croc (Waylon Jones), Mr. Freeze (Victor Fries), and Ra's al Ghul (Head of the Demon).
- Mad Hatter turns himself in at GCPD Headquarters and claims that he has kidnapped three police officers. It is up to Batman to find them before they fall victim to Tetch's mad games.
- Batman discovers that there are now two factions of the League of Assassins and he must stop them both before they destroy Gotham.
- Iron Heights Penitentiary has crashed in Gotham Bay and now Killer Croc is leading a riot with the other inmates.
- Mr. Freeze has returned to Gotham and his wife has been taken by the Militia. Batman must team up with the cold hearted scientist to save her.
- Alfred Pennyworth (Voice and hologram only)
- Aaron Cash
- Killer Croc (Beneath the Surface)
- Nightwing (Beneath the Surface)
- Iron Heights Prisoners (Beneath the Surface)
- Warden Ranken (Beneath the Surface)
- Prison Officer Griscelli (Beneath the Surface)
- Prison Officer Burfitt (Beneath the Surface)
- Prison Officer Riley (Beneath the Surface)
- Prison Officer Blackburn (Beneath the Surface)
- Mr. Freeze (In From the Cold)
- Nora Fries (In From the Cold)
- Arkham Knight (In From the Cold)
- Deathstroke (In From the Cold)
- Arkham Knight's Militia (In From the Cold)
- Mad Hatter (Wonderland)
- Mad Hatter's Henchmen (Wonderland)
- Officer Katz (Wonderland)
- Officer McQueen (Wonderland)
- Officer Hutch/Sergeant Lory (Wonderland)
- TYGER (Wonderland)
- Joker's Henchmen (Wonderland)
- Blackgate Prisoners (Wonderland)
- League of Assassins (Shadow War)
- Ra's al Ghul (Shadow War)
- Nyssa Raatko (Shadow War)
- Talia al Ghul, referenced only confirmed deceased (Shadow War)
- Hugo Strange, referenced in one of the secret tapes (Shadow War)
December 22, 2015.
- The Scene of the Crime – Rescue Mad Hatter's first hostage.
- Head Games – Rescue Mad Hatter's second hostage.
- In Storybook Endings – Lock up Mad Hatter in GCPD.
Beneath the Surface
- The Beast Beneath – Defeat the prisoners.
- Breaking the Skin – Gain access to the high security area.
- Evolution – Lock up Killer Croc in GCPD.
In From the Cold
- Cold Case – Interrogate the Militia Lieutenant.
- Out in the Cold – Track down the cryopod.
- The Resurrection and the Life – Survive the Militia onslaught.
- The Demon Lives Again! – Follow the Assassin's trail.
- Daughter of the Demon! – Discover the Lazarus Pit.
- Ashes to Ashes – End the League of Assassins' war.
- This is the only Arkham Knight DLC to add extra side missions rather than standalone content like the Arkham Episodes.
- The only villain to make a cameo in the original game is Killer Croc in a fear gas hallucination scene with him teaming up with Two-Face, The Riddler and Penguin. The other three villains in the pack were mentioned in Gotham City Stories.
- Out of the four villains, Mr. Freeze isn't considered an antagonist. Instead, the Arkham Knight/Deathstroke/Arkham Knight's Militia play this role in In From the Cold.
- Beneath the Surface is similar to Batman: Arkham Asylum in some ways. Batman must go to a prison where prisoners are escaping. The warden of the facility is secretly evil. Batman is getting help from an apprentice.
- After installing the DLC, extra areas show up, such as a different portion of the GCPD Building (which includes an Evidence Cabinet, another Interview Room and the Maximum Security West Wing) and the Elliot Memorial Hospital (previously inaccessible).
- Oddly, even if one is to play the DLC after defeating the Arkham Knight, he may still shout orders when fighting the Militia when playing through The Resurrection and the Life.
- Even if City of Fear isn't completed, The Joker's hallucinations don't appear in all four of the DLC missions.
- The missions are partially inspired by Batman: Arkham Asylum, according to Rocksteady Studios.
- After completing all four missions, there are still three empty cabinets left in the second Evidence Room.
- In a way, most concepts from each villain are similar to their Animated Series counterparts.