The ADAM Beast is an incredibly powerful foe Conner will have to face multiple times throughout the game, and has become a legend throughout Rapture.
The ADAM Beast was believed to be a man who came to Rapture to be one of the first test subjects for refined ADAM, resulting in the man suffering through numerous ADAM injections, early Plasmid tests, and even early Gene Tonic tests. After mutating incredibly from the massive ADAM injections, the ADAM Beast was locked up in a hidden underground cell lab for misfit ADAM test subjects, resulting in it devouring it's fellow inmates, taking all their ADAM in the process. After a few years of breaking through the wall in it's cave and taking ADAM slugs to help stabilize it's ADAM need, it was eventually freed by Conner by accident when Conner was forced to open all of the underwater hatches in order to stabilize the water pressure in New Rapture near the beginning of his adventure. Incredibly powerful and almost invulnerable, Conner must find other ways to defeat this enemy, such as electrical conductors or lava tanks.
Crushing Blow: The ADAM Beast lifts his fists to the sky, slamming them into the floor, causing a large earthquake that will throw back Conner and cause him to fall to the floor, stunned. This attack can easily be avoided by jumping up before the shock-wave reaches Conner. (There is a slim chance that the ADAM Beast will accidentally get his arms stuck in the floor, leaving him vulnerable.)
Death Roar: The ADAM Beast lifts it's head and let's loose an ear-splitting roar, causing Conner's sight to blur and his movements to be sluggish and slow for the duration of the effect. This is one of the few attacks Conner can not dodge or escape from. (While roaring, the ADAM Beast's Sea Slug covered chest is vulnerable, Conner can aim and shoot at the ADAM Beast's soft belly and get direct damage, however, it is incredibly hard to aim considering the roar is in effect.)
Maw Crush: The ADAM Beast lifts it's head back and tries to eat Conner, resulting in Conner taking continuous damage as the ADAM Beast gnaws on him before spitting him out, further damaging him if he hits a wall or object. This attack can be avoided by swiftly moving to the side. (Although it is a slim chance, the ADAM Beast can get it's mouth stuck in the floor, wall, or ceiling, leaving it vulnerable. Conner can also escape the ADAM Beast's gnawing by pressing the Y (Jump) button, the A (Interact) button, the X (Shoot) button, or the B (Melee) button. The Analog Stick (Movement Key) can also be used, however, it does not do any damage to the ADAM Beast, but unlike it's counterparts, it is quicker and easier to use.)
Speed Boost: The ADAM Beast uses a kind of Aero Dash/Speed Booster tonic, increasing it's overall attack speed. This attack is one of the few which does not harm Conner directly. (The ADAM Beast will raise it's whole body like a stallion for a moment, with it's vulnerable underside showing. This will make for some easy pot-shots.)
Law Of The Jungle: The ADAM Beast will drain all nearby enemies of their ADAM via devouring them, healing itslef in the process. This attack is one of the few attacks that does not harm Conner in anyway. (Like Speed Boost before it, the ADAM Beast will be vulnerable to attack while using this move as it in the posture of a bear when using this move, revealing it's soft underside.)
Venomizer: Once the player roams too far away from him, the ADAM Beast will spew a purple-like liquid at the player from it's mouth, resulting in Conner to be stuck at his current location for a few seconds. The player can escape from the liquid by rapidly moving the Movement Key.
Tail Whip: The ADAM Beast suddenly whips his tail, either knocking Conner off his feet or making him fly into wall, dealing moderate damage. (If Conner falls, the ADAM Beast will try to jump onto him and crush him underneath his feet, causing a quick-time event which causes Conner to roll away and jump up to his feet. If Conner hits the wall, the ADAM Beast will try to grab him and crush him, causing a quick-time event causing Conner to suddenly slump to the floor and run away.)
Fatal Attraction: The ADAM Beast suddenly inhales greatly as it is in the posture of a four-legged animal. This causes all objects, enemies, and Conner himself to be pulled toward it's large mouth. Conner can avoid this attack by hiding behind a stable wall. (Eventually, all cover will be gone.) If he does not, he will be sucked into it's mouth and be forced to finish a quick-time event, causing Conner to push open the ADAM Beast's mouth, escaping, and then ripping out one of it's teeth to finally stab it in the eye before he jumps off of it. (The player will actually be forced to complete this task the first time they are sucked into it's mouth.)
Credit goes to RaptorBarry for art.