Manny Jacinto's Qimir has become one of my favorite SW-villains despite his limited screen time. The others on this list were fantastic, too, particularly James Earl Jones and Ian McDiarmid.
But Qimir has given me the creeps like few other villains. He singlehandedly elevated The Acolyte by a couple of tiers for me. Aura, performance, writing, design, and the skills displayed in the action scenes were all outstanding. Even if we won't get more of Jacinto's performance as Qimir, I think he's a noteworthy villain in the SW-universe