Darth Maul: The Intimidator.

Form 7; Juyo/Vaapad
Dubbed the Way of the Vornskr or The Ferocity Form, Juyo, a term from High Galactic, was originally considered an incomplete form for millennia. Generally viewed as undeveloped and rarely used by the Jedi and the Sith, Juyo was not seen as one of the main forms for generations of Jedi. Jedi Master Mace Windu completed Form VII when he developed the form of lightsaber combat known as Vaapad, named after a creature from Sarapin which moved with incredible speed. It was considered the most powerful form, but because of the intensity involved, it was thought dangerous because it bordered on the Dark Side of the Force. Practitioners of Vaapad included: Mace Windu, (creator) Depa Billaba, Sora Bulq (co-creator) and Quinlan Vos (incomplete) Practitioners of standard Juyo include General Grievous, Darth Maul, Zez-Kai Ell, Vrook Lamar, Kavar, and Kas'im. Count Dooku seemed to know enough of the Juyo form to teach General Grievous and his IG-100 MagnaGuards, so he is a possible Juyo practitioner. Vaapad is believed to have been lost with the death of Mace Windu, as no records exist of its instruction after the end of the Clone Wars and the start of The New Jedi Order. The entirety of the form itself is believed to have died with Palpatine. Until one day the last of scrolls of the teaching of this powerful form were found by Darth Loco in an abandoned temple in an unknown loacation. Darth Loco took the scrolls and began is journey in learning the powerful form.