Tarkin. We didn't see him necessarily die, nor was it mentioned in later movies. Plus he has that whole "Cultured British Evil Style" working for him.

http://en.wikipedia.org/wiki/Peter_Cushing

Sorry, but i think more often about his old Hammer Film roles ...

I've been toying with the idea as Asoka becoming a Sith Lord, Darth Ashok.

She leaves the order, goes off on her own. Upon hearing Padme died and Skywalker becomes Vader, she returns, professes her love for him, only to be shunned, and even hunted down. These turn of events drive her to the dark side; she goes into hiding, trains (somehow) to prove her worth as Lady Vader. When Vader dies in RotJ, this leaves a void that she will eagerly fill.

Or something like that...

I've been toying with the idea as Asoka becoming a Sith Lord, Darth Ashok.

She leaves the order, goes off on her own. Upon hearing Padme died and Skywalker becomes Vader, she returns, professes her love for him, only to be shunned, and even hunted down. These turn of events drive her to the dark side; she goes into hiding, trains (somehow) to prove her worth as Lady Vader. When Vader dies in RotJ, this leaves a void that she will eagerly fill.

Or something like that...

Her and Ventress team up? Starting a second sith cell? This has potential.

I've been toying with the idea as Asoka becoming a Sith Lord, Darth Ashok.

She leaves the order, goes off on her own. Upon hearing Padme died and Skywalker becomes Vader, she returns, professes her love for him, only to be shunned, and even hunted down. These turn of events drive her to the dark side; she goes into hiding, trains (somehow) to prove her worth as Lady Vader. When Vader dies in RotJ, this leaves a void that she will eagerly fill.

Or something like that...

There are plenty of "Jedi" that fall to the Dark Side and train themselves to be powerful foes. Untrained, but powerful. I see Asoka as having enough training to be competent, but not enough to fall and become even more deadly to those around her and herself.

Only problem with some of the Clones: many were old and/or dead by the time the Rebellion Era rolled around. I mean, the Clone Wars went on for a few years, and it was another. . .30 years, was it, until the Rebellion Era swung on in high gear?

While they can be powerful in some ways, these are career soldiers, grunts more often than not, who are not up for the same degree of work they used to be. That's not to say they can't be an annoying, recurring villain that appears from time to time, but they may have to be more behind the scenes rather than upfront.

On the other hand, one only has to look at recent action movies features stars in their 50s and 60s like Willis, Schwarzenegger, Stallone and Liam Neeson...

I can totally see Rex or Cody ending up an action character like that, whether on the side of the Empire or against it.

I remember from The Force Unleashed 2 that there was an encyclopedia blurb regarding Stormtroopers no longer being of Clone stock, and Cody's lament about how many of the Clones were either too old to fight or simply died in battle. This makes me wonder if the aging process really did slow to "normal" after they were "finished" or if there were simply so many Clone losses after the rise of the Empire.

That said, I won't disagree that they can be awesome action characters, but a character I'd keep in reserve for a rainy day and/or when I really, really want someone that can give the party hell.

whatever happened to Sate Pestage?

OP, are you looking to use someone without post-ABY0 canon in order to avoid disrupting what happens later (ie - they get killed by the players)?

I liked the idea of Asoska falling in love with Boba Fett and being expelled from the Jedi Order. She becomes bitter and ends up heading to the outer rim to escape vader.

whatever happened to Sate Pestage?

OP, are you looking to use someone without post-ABY0 canon in order to avoid disrupting what happens later (ie - they get killed by the players)?

Exactly, especially one that does not alter cannon if killed. .....

I'm trying to work Mara Jade in as a nemesis in the opposite fashion you are looking for...I know when I need to stop using her.

My plan is to completely avoid any direct confrontations to avoid her being killed (hopefully) and having her primarily act through intermediaries...only directly interacting with the PCs in situations where combat would be inadviseable.

For starters she was instrumental in the abduction of a Force Sensitive PC who has no powers yet (only edges from the FS tree) and isn't even aware he is FS(in game of course)...the thought being the Emperor is always interested in potential new students and this one is untainted by any Jedi teachings...so he is a captive on Trex's ship when it is hijacked by the PCs (the player missed the basic game intro adventure). Of course Mara was too busy to transport him herself so she hired this flunky for transport to Coruscant.

The player has no idea its Mara so I'm not set on this course yet...going back to research her earlier canon so I don't mess it up too much.

Also, in the most recent issue of Insider, and also recapped on Wookieepedia is a fallen Jedi named Malleus, the Hammer of the Dark Side, using Warb Null's armor. I guess he's brand new, so no canon yet.

You could even go the posession route with someone else, or (what was that thing from Dark Horses Vector crossover called?).

Just throwing those out there.

Did they ever explain what happened to Zayne?

You're dealing with 20 years of unfilmed story between Episode III and Episode IV. Star Wars: Rebels will be introducing some new characters during that time span but you're hard pressed to find a character who's still a viable threat, especially if they're human. That said, some possibilities include:

• Gorga the Hutt was still alive after Darth Maul and Death Watch gunned down the other members of the Hutt Council as he took shelter with Jabba.
• Sly Moore was Palpatine's aide. According to the EU, she was an Umbaran Force sensitive adept so she could be a threat.