BBBLP
Robot Rock
Lets try to compile a list of all background characters.
Swampthing - Swimming in Atlantis background
Giganta - Fighting in Hall of Justice
Atom Smasher - Being a badass in Hall of Justice
Gorilla Grodd - Fighting guards in Stryker's Island
Killer Croc - Teasing me in Arkham Asylum
Penguin, Two Face, Riddler - Stage interaction in Arkham Asylum
Scarecrow - Chilling in his cell in Arkham
Martian Manhunter - Floating around in the Watchtower
Doomsday - Standing in the background of Fortress of Solitude
Only ones I could recognize
Swampthing - Swimming in Atlantis background
Giganta - Fighting in Hall of Justice
Atom Smasher - Being a badass in Hall of Justice
Gorilla Grodd - Fighting guards in Stryker's Island
Killer Croc - Teasing me in Arkham Asylum
Penguin, Two Face, Riddler - Stage interaction in Arkham Asylum
Scarecrow - Chilling in his cell in Arkham
Martian Manhunter - Floating around in the Watchtower
Doomsday - Standing in the background of Fortress of Solitude
Only ones I could recognize