Ace the Bathound is one of the Blind Bag characters in LEGO Dimensions 2: The Rise of Enoch, from the DC Comics franchise.
Ace was the guide dog of a blind native American named Black Wolf, who just called him "Dog". After helping Batman against some criminals and Black Wolf's subsequent death, Batman adopted Dog and renamed him Ace.
Ace also known as Titus lives in the Batcave and sometimes helps in cases where his sense of smell is useful. He is very affectionate towards Batman. Occasionally, Ace will help Batman or Krypto (the Super-Dog) to fight crime.