A True Alpha is a canine werecreature who is said to become an alpha solely by the strength of their character, their virtue and sheer willpower. They are the rarest kind of alpha, shrouded in myth and said to appear once in a 100 years.

 

Given this rarity and mythical status, the information stated about them (and on this page) may be subject to hyperbole or distortion from being passed down through the centuries. Scott's statement of "I'm a true Alpha. You have no idea what I can do." in 3x17 - Silverfinger is a subtle bit of lampshading to this point as neither the Twins, Scott, nor the audience truly know what a True Alpha can do. That said, here are a few more points of what we have been told or have observed:

 

Supernatural Rules 

A werewolf cannot attain True Alpha status if they ever kill someone.

 

A True Alpha's power can only be taken by a beta turned by their own bite.

 

Series

In Season 3, Scott McCall's eyes, during situations of high duress but sheer determination, briefly turn alpha red. In Currents, Alan Deaton confirms Scott has the potential to become a True Alpha. 

 

In Lunar Ellipse, Scott rises the alpha rank by determinedly pushing through a mountain ash barrier, successfully breaking it, fully awakening his True Alpha power.