The Big Daddy is a powerful boss-like enemy from the the BioShock franchise - although often referred to as singular there are numerous Big Daddies in the storyline and they are all heavily–spliced former humans encased in huge suits of armor that are incapable of speech except for moans. Their purpose is to protect the Little Sisters, little girls who the player must either kill or rescue and turn into normal little girls, and they will do their job with brutal efficiency if necessary. The two types of Big Daddy in the original Bioshock are the Bouncer and the Rosie. Bioshock 2 introduces the Rumbler, the Alpha Series (the very first Big Daddies), and the Big Sister (they are former Little Sisters who have grown up), and the DLC Minerva's Den introduces the Lancer, said to be the most advanced Big Daddies of all.
Bioshock Infinite, which is about another completely different fictional city in the same universe, replaces the Big Daddies with a singular giant robotic bird called the Songbird.
The Big Daddy has become one of the most recognizable aspects of the BioShock franchise and also the series mascot among the enemies.