Personal Info:
Leader(s): The Batman Who Laughs
Also Known As: Robins
Purpose: Pets of the Batman Who Laughs
First Appearance: Dark Nights: Metal Vol.1 #1 (2017) Modern Age Villain
Known Associates: The Batman Who Laughs, The Dark Knights, Robin King
Base Of Operations: Mobile
Grudges: Batman and the Justice League
Creators: Scott Snyder and Greg Capullo
Groblins are of limited intelligence but loyal to the Batman Who Laughs. They are vicious and cannibalistic.
Claws and Teeth: Groblins possess sharp claws and teeth.
On the Batman Who Laughs' home world of Earth -22, in an effort to drive the Bat insane, the Joker temporarily paralyzed the hero and forced him to watch as he recreated the Wayne murders on a long line of captured children and their parents - shooting each of the children's parents and then infecting the orphans with an incurable strain of Joker Venom.
After Batman had broken free and finally killed the Joker, he collected all of the infected children and had them kept together in an effort to find a cure. However, because Batman had been exposed to a toxin released upon the Joker's death, he slowly started to become the new Joker himself and soon re-purposed the Jokerized children as his new pets - dressing them up in Robin costumes and training them to listen to his commands.
Groblins at DC Database