Beast Within

Beast Within is a series of transformational techniques that Bayonetta can earn or purchase from The Gates of Hell. It is unlocked after Chapter 5 in the first game, Bayonetta and returns as a feature in the sequel game. Both Umbra Witches and Lumen Sages possess the same ability, as revealed by Balder in the second game, Bayonetta 2. So far we don't know if it'll be in Bayonetta 3.

In-Game Description (Bayonetta)
"Unleashing the Beast Within allows you to transform into an animal form and unlock mysterious magical powers."

Panther Within

 * Animal: Black Panther
 * How to Obtain:
 * Bayonetta: Unlocked/earned after Chapter 5.
 * Bayonetta 2: Automatically obtained at the start of Chapter 1.
 * Description: Bayonetta transforms into a black panther and is able to run very fast as well as make long jumps/double jumps.
 * How to activate:
 * Bayonetta: Double tapping  while on the ground.
 * Bayonetta 2: Double tapping ZR while on the ground.
 * Attack: In Panther Form, Bayonetta will swipe at an enemy with her claws.
 * Jeanne's Equivalent: Lynx Within
 * Rosa's Equivalent: Tiger Within
 * Balder's Equivalent: Wolf Within

Crow Within

 * Animal: Crow
 * How to Obtain:
 * Bayonetta: Unlocked after Chapter 5; must be purchased for 20,000 Halos at The Gates of Hell.
 * Bayonetta 2: Unlocked after Chapter 1; must be purchased for 20,000 halos at The Gates of Hell.
 * Description: Bayonetta transforms into a large crow. This form allows you to fly for a short period of time, it can help you make a jump you couldn't previously or give you a few more feet after a jump.
 * How to activate:
 * Bayonetta: Double tapping  in mid-air.
 * Bayonetta 2: Double tapping ZR in mid-air.
 * Attack: Use feathers as a weapon. Press to summon a group of feathers, press it again to stab enemies. Press to summon a ring of feathers, press it again to shoot them around you.
 * Jeanne's Equivalent: Owl Within
 * Rosa's Equivalent: Falcon Within
 * Balder's Equivalent: Eagle Within

Rodin's equivalent:''' None

Bat Within

 * Animal: Swarm of Bats
 * How to Obtain:
 * Bayonetta: Unlocked after Chapter 5; must be purchased for 20,000 Halos at the Gates of Hell.
 * Bayonetta 2: Unlocked after Chapter 1; must be purchased for 20,000 halos at The Gates of Hell.
 * Description: Bayonetta transforms into a swarm of bats when she dodges at the last second. This escapes the attack, pushes the enemy away and can activate Witch Time. This is purely defensive, however the slightest bit of damage will be delt to the enemy.
 * How to activate: Dodge at the instant an attack hits.
 * Jeanne's Equivalent: Moth Within
 * Rosa's Equivalent: Hornet Within
 * Balder's Equivalent: Unknown

Snake Within

 * Animal: Cobra snake
 * How to Obtain: Obtained automatically in Chapter V.
 * Description: Bayonetta transforms into a long cobra that allows her to glide through underwater locations whenever this is activated. This form acts as an underwater equivalent to Panther Within.
 * How to activate: Double-tap ZR underwater.
 * Jeanne's Equivalent: Centipede Within
 * Rosa's Equivalent: Cobra Within
 * Balder's Equivalent: Unknown

Squirrel Form
Loki has an ability similar to the Beast Within in which he turns into a Flying Squirrel. While in this form, Loki can glide and move around quickly, though he mainly uses this form to ride Bayonetta around to keep out of the way and trouble.

Trivia

 * The Umbra Witches' and Lumen Sages' forms as cats and canines, respectively, further symbolized the rivalry between the Witches and Sages, as cats and dogs are usually depicted as enemies in fiction, just like the Witches and Sages were.
 * Bayonetta, Jeanne and Rosa taking the form of different species of cats refers to the myth that witches could transform themselves into cats in order to kill or smother people in their sleep, along with their association with witchcraft and the devil during the medieval european witch trials.
 * In a brief scene in Bayonetta 2, Bayonetta and Balder talk to one another as they are in their panther and wolf forms. This suggests that a Witch or Sage can still speak even if they are in animal form.
 * Bayonetta's serpentine form is referred to as the "Snake Within" while Rosa's is referred to as the "Cobra Within", even though Bayonetta's serpentine form resembles a cobra and Rosa's resembles a normal snake.