It sounds like you're asking about the character who laughs in relation to Batman. The most iconic character known for his distinctive, maniacal laugh in the Batman universe is The Joker.

The Joker: Batman’s Laughing Nemesis

• Who is The Joker?
  The Joker is Batman’s arch-nemesis, a psychopathic criminal mastermind with a clown-like appearance. He is infamous for his chaotic nature and dark sense of humor.

• Why does he laugh?
  The Joker’s laugh is a signature trait that reflects his madness and unpredictability. It’s often described as a chilling, maniacal cackle that symbolizes his twisted worldview and enjoyment of chaos.

• Relationship to Batman:
  The Joker’s laughter contrasts sharply with Batman’s serious and brooding demeanor. Their dynamic is central to many Batman stories, with the Joker often using his laughter to taunt and unsettle the Dark Knight.

If you want to know more about Batman or other characters who laugh in the Batman universe, feel free to ask!