Super Saiyan

This is the first of MANY Super Saiyan transformations which began as a simple legend that appeared every once in a million years or some such.
The form was first obtained by Bardock, as Bardock had been sent back in time, although this may be non-canon. After that, the form was unlocked by Goku, and blah blah, you know that whole story.
ONTO THE SEXY STATS (not really)
The Super Saiyan form gives the user a Power Multiplier of 50, and the Ultra and Ascended forms give you roughly a x65 - x75 increase.
It was believed for a time that Super Saiyan was only obtained to a response to a need or desire. However the importance-shattering assholes known as Goten and Trunks tore that right up.
The mythical transformation comes in four different grades, the first having a multiplier of 50. The second grade, also referred to as Super Vegeta gives a x75 multiplier. Grade three gives a x100 multiplier, and grade four, though not confirmed, gives a x150 multiplier.