Quinlan Vos had a complicated relationship with the Dark Side. While a far cry from an actual Sith, Vos got up to all kinds of skullduggery as a double-agent under Count Dooku. He fed information on the Separatists' droid army to the Jedi, sure, but he also cut his great-aunt Tinté in half. As Luke Skywalker can attest, aunts get a pretty raw deal in the Star Wars universe.
Granted, Tinté wasn't all that familial. She had sacrificed her nephew's parents to vampires that suck people's brains out through their noses several years before. And that was just the first in a string of pretty gnarly things that probably led to Quinlan getting so cozy with the Dark Side. Star Wars is weird, by the way.
Vos continued to dance between the light and dark throughout the Clone Wars. He got so good at it, in fact, that pretty much every other Jedi in the universe thought he really had become a baddie and ostracized him from the order. It didn't stick, however, and by the time the future Emperor Palpatine started killing all of the other space wizards Vos was entirely on the side of the angels. He enjoyed it just long enough to be blown up on top of an exploding tank on the Wookiee home world, Kashyyyk. Death didn't stick so much either, as it turned out. He went into hiding, healed up, and went on to start a new life with a wife and kid. Who says killing your loved ones has to end with you being burned alive and turned into a ruthless cyborg?
Rahm Kota might just be one of the only Jedi of his era with good sense. For some reason, the elderly Jedi didn't trust a batch of secretly cloned and mysteriously funded super-soldiers. Instead of taking up a General's position during the Clone Wars, Rahm formed his own militia of volunteers. As such, when Order 66 went out nobody in his immediate vicinity was listening. Lucky him!
He and his homespun boys and girls proceeded to work in secret against the Empire for quite some time after that. Sadly, Rahm made the mistake of wanting to take out a relatively low-level government official called Dark Lord of the Sith Darth Vader. Vader, thinking Rahm might make a pretty amusing Sunday afternoon diversion, sent his secret apprentice, a.k.a. Galen Marek, a.k.a. Starkiller, to whoop him for his amusement. And that's exactly what happened, because when someone called "Starkiller" decides to give you a whooping somebody called Starkiller gives you a goddamn whooping.
Beaten, blinded, but fortunately not dead, Rahm went back into hiding to fight a new enemy: alcoholism. Yeah. Apparently, getting beaten just the once was enough to sever his connection to the Force and build one with a bottle. Things improved after he ran into Vader's apprentice a second time. Together, the two teamed up along with some important senator types -- including Mon Mothma and Princess Leia's adoptive father Bail Organa -- to start the Alliance to Restore the Republic. You might know it better as the Rebel Alliance.
More general treachery and backstabbing ensued for a while. In the end, though, Rahm wound up with the General's rank he had originally turned down. This was after he went toe-to-toe with Darth Vader and Emperor Palpatine himself. He even infiltrated the freaking Death Star in order to rescue a horde of prisoners, right before one Mr. Skywalker blew the space station into concentric rings. Never underestimate a backwater hick with the Force on their side.