Batman: The Dark Knight Bat-Signal

The Bat-Signal is a distress signal device appearing in the various interpretations of the Batman mythos. It is a specially modified searchlight with a stylized symbol of a bat attached to the light so that it projects a large Bat emblem on the sky or buildings of Gotham City. In the stories, the signal is used by the Gotham City Police Department as a method of contacting and summoning Batman to their assistance in the event of a serious crisis and as a weapon of psychological intimidation to the numerous villains of Gotham City.