|A Big Daddy, aiming to attack.|
One of the tougher enemies in the game, the Big Daddy's primary goal is to protect Little Sisters. Contradictory to what first timer's may assume, they will not attack unless provoked, either by their being attacked, or a Little Sister. Getting near either may cause them to be aggressive, but no serious damage will be dealt. When you see Big Daddies roaming around alone in different stages it is quite safe to run past them even at close proximity (eg in corridors or stairwells).
When attacking or attempting to attack, the lights on the front of their suit will turn red, as pictured to the right. This is a primitive behaviour exhibited by some members of the animal kingdom in real life, perhaps attesting to the Big Daddy's primitive nature and stature. When neutral, the lights will be yellow, and when hypnotized, they'll be green.
There are two types of Daddies: the Rosie and the Bouncer (the latter is shown here). The Rosie is a long-range fighter, equipped with a rivet gun and proximity mines. The Bouncer is a short-range fighter which attacks with its drill, and is known to both charge at the player at incredible speeds, and stamp the ground with its massive feet, stunning the player and making it difficult to move or escape.
Very tough at first, Big Daddies become easier over time the more progress is made with photography research on the enemy, and once the Crossbow and Grenade Launcher are obtained (both especially effective weapons against them).
Big Daddies were created by Suchong after he realised Little Sisters needed some form of protection while gathering ADAM. They are created by taking a man and having his skin and organs grafted directly into a Big Daddy suit.