Darth Vectivus

Darth Vectivus was the most boring Sith Lord ever to exist in the history of the galaxy. He was a pudgy, doughy guy who delved into the philosophies of the Sith and the mysteries of the Force, but never used it to take over the government (because he didn't mind how the government was running) or to murder millions of people (because many of those people were voluntarily producing goods and services he wanted). He just went into business for himself, became incredibly rich, build magnificent mansions for himself and his loving family, and died peacefully in his sleep.

Darth Vectivus always said "please" and "thank you." He contributed to charity to bolster his public image. He always recycled his aluminum cans. In his spare time he worked to bolster the populations of endangered animals. His "Rearden metal" provided the basis for a new generation of starships that safely carried billions of sentient beings through the galaxy for years. BORING! He was as boring as the Gonkerson family. About the most evil thing he did in his life was listen to Rush Limbaugh. And even that was only once or twice a week.

Lumiya was shocked to learn such a mild, unobtrusive Sith ever existed and made a point of showing his old mansion to Jacen Solo, who looked back at the life of Darth Vectivus and decided being a Sith Lord wasn't so bad, so he became Darth Caedus. Slight problem, Darth Caedus actually was evil and actually did take over the government, so whoops, wrong lesson learned.