Ace the Bathound has taken on many forms over the years. From simple inclusion in the comics, to becoming a full fledged characters in several TV series. Ace is fiercely loyal to Batman, and when the opportunity arrives, he'll happily defend his master and attack those who dare threaten him.
His two most iconic roles arguably are in Batman Beyond, where he served as a great asset to both Bruce Wayne and Terry McGinnis, and in Krypto: The Superdog show, where he was basically Batman...but as a dog. Either way, Ace is a fully accepted member of the Batfamily by many in the fanbase.