Tweedledum and Tweedledee were two villains who were referred in the Batman Arkham games series.
History[]
Batman: Arkham Asylum[]
While Tweedledum and Tweedledee do not appear in Batman: Arkham Asylum, their matching hats are seen sitting on a seesaw near the entrance gate at Arkham North. He and his cousin had their page with a Riddler question mark, which they are known for their plans and their obsession with Wonderland. Riddler might have let them out, since part of their uniforms are on the seesaws which they play in the Lewis Caroll's book.
Batman: Arkham City[]
In the Arkham comics, him and Tweedledum were being escorted by TYGER guards, as a result of being captured, however, Riddler is observing them being captured which supports that Riddler is working with both Tweedledee and Tweedledum.
Batman: Arkham Unhinged[]
In the Batman: Arkham Unhinged, it is revealed that Tweedledee and Tweedledum are working with Mad Hatter. They disguised themselves as police and escorted Vicki Vale to a trap set by the Hatter to reclaim his Alice.
Batman: Arkham Knight[]
In the prequel comics to Batman: Arkham Knight, it's hinted that both Tweedles, along with a third Tweedle: Tweedledie, are killed by the Arkham Knight.