Riot Shield

Riot Shields are weapons used by enemies from Batman: Arkham City, Batman: Arkham Origins, and Batman: Arkham Knight. They render their carrier untouchable by regular attacks, which forces the player to use advanced tactics against them. The easiest way to attack their carriers is to perform a Cape Stun and then perform an Aerial Attack. They can also be taken out with a Special Combo Takedown, and the shield can be destroyed with the Disarm and Destroy move.

Batman: Arkham Origins Incident
Enemies used shields even during Batman's second year as a vigilante. The first shielded enemy was fought after exiting the Lacey Towers crime scene.

Batman: Arkham City Incident
Enemies still used Shields during the Arkham City Incident. Batman first encountered them during his visit in the sewers under Arkham City.

Batman: Arkham Knight Incident
Shields were still being used by enemies during the events of Arkham Knight. Militia Brutes would use their suits tech to activate the shield.

TYGER shield
During the events of Batman: Arkham City, TYGER forces use military-grade anti-riot shields with a clear armored viewing port. These shields are adorned with their logo in the center.

Car Door
In Arkham City and Arkham Origins, select thugs will use makeshift shields from car doors that emulated the effectiveness of anti-riot shields.

Police shield
During the events of Arkham Origins, members of the police swat division in Gotham City will use police-issue riot shields. These are black with the word "Police" on it and a clear armored viewing port, similar to the TYGER riot shield.

Trivia

 * Within the Cyrus Pinkney Institute for Natural History is a display case holding a TYGER riot shield. When interacted with, Penguin will say that the shield can "block a nine mill at close range and keeps you warm in the cold".