The comic book character Ace the Bat-Hound was the canine crime-fighting partner of Batman and Robin in DC Comics of the 1950s and 1960s. Inspired by the success of Krypto in the Superman comics of the same period, Ace debuted in Batman #92 (cover-dated June 1955). He was created by writer Bill Finger and artist Sheldon Moldoff , who said the character was inspired by Rin Tin Tin.

Ace was a German Shepherd originally owned by an engraver named John Wilker. He was found by Batman and Robin after his master was kidnapped by a gang of counterfeiters. Batman used Ace to try to locate Wilker. Because he had already placed a large number of "lost dog" announcements for Ace in his civilian identity of Bruce Wayne, he was concerned that anyone recognizing Ace (who had a prominent star-shaped marking on his forehead) might make the connection between Bruce Wayne and Batman. To forestall that problem, he hastily improvised a hood-like mask for the dog that also incorporated the bat emblem as a dog tag dangling from Ace's collar. Ace was subsequently christened "The Bat-hound" by a criminal he helped Batman to apprehend.

Wilker later took a new job that made it difficult for him to take care of Ace, so he left the dog to Bruce Wayne. Wilker was never aware that Ace was the Bat-Hound or that Bruce Wayne was Batman.

Ace disappeared from the Batman comics after Julius Schwartz took over as editor in 1964, and made only very occasional comic book appearances (such as in Ambush Bug #3, 1984) in the years afterward.

A modern-day version of Ace was reintroduced in Batman #462 (1991), although he has been little seen in recent years.

In the late 1990s animated series Batman Beyond, an aged Bruce Wayne had a pet/guard dog named Ace, a Great Dane, but there were no indications that he'd ever used that incarnation of Ace as a crime-fighting assistant. However, one episode revealed Ace, as a puppy, was bought from a pet store by a cruel man who forced dogs to fight one another gladiator style for the amusement of paying crowds. Ace escaped this abusive, violent life. He soon found Bruce, a fellow tormented soul, and the two got on well. Young Terry McGuiness, Wayne's assistant and protegee, seemed to be the only other person Ace ever cottoned to.

In the 2005 Cartoon Network animated series Krypto the Superdog, Ace makes occasional appearances, and is once again a crimefighting ally of Batman. In this series, Ace is equipped with various gadgets and equipment as an aid in his crimefighting efforts.