Batman: Arkham - Ranking EVERY Villain Worst To Best

The final boss of Batman: Arkham City is an ingenious bait-and-switch, and, unless you've played the game before and are looking out for any hints, there's almost no way you could have guessed how this ending would turn out.

Unbeknownst to anyone but himself and Harley Quinn, the Joker, deathly ill from his overdose of Titan in the previous game, enlists the shapeshifting Basil Karlo, aka Clayface, to pose as him while he waits for Batman to find a cure.

Karlo first appears in a cell in Arkham Asylum, taking the form of Batman's allies, Aaron Cash and Commissioner Gordon. The debut of his Clayface form, however, comes in the finale of Arkham City, when Talia al Ghul stabs 'Joker' through the chest, only for him to melt into clay and reveal his true identity.

Karlo, formerly a stage actor, considered impersonating the Joker "the role of a lifetime" - but that role is soon brought to an end when Batman destroys his corporeal body in the Lazarus Pit.