Many villains and the good guys of Dragon Ball undergo changes in order to increase their fighting strength. These changes sometimes take a long time and others are quick, despite the amount of time, it definately gives each of them a power boost. Below are characters who achieve these transformations, click on one of the character's image to see all of their forms and info on them.

Cooler:

He is Frieza's brother and like him he undergoes through a few changes himself. Although he has a few more changes the first three are never shown in the series. Here you'll be able to see his last two forms and his modified form.

Frieza:

He is Cooler's brother and he has the ability to make four different transformations. Here you'll be able to see his four forms and his modified form.

Janemba:

He started off a fat blubblery being with a child-like attitude. Once he transformed though he became incredibly powerful, and neither Goku nor Vegeta can beat him at full strength. Here you can see all of his forms.

Majin Buu:

Majin Buu is one of the most complex characters to understand since you see so many variations of him in the series. Although he goes through many transformations most of them are by absorbing other beings. Here you will see every single one of them.

Perfect Cell:

He is the only android who can go under many changes. Cell had to go through many transformations in order to become perfect. Here you will see him from his egg form to his fully perfect form.

Rilldo:

Rilldo is the metal creation of Dr. Myuu. This metal monster only has three transformations but each one can lead to devastating consequences. Here you can see his three metal transformations.

Saiyans:

All of the Saiyans can achieve different levels of power with intense training. The rage of a Saiyan is what makes them undergo the change, here you can see all of the possible levels a Saiyan can reach.