Another fine idea is one of the Jango Fett clones; toward the end of the Clone Wars, Palpatine started mass cloning that wasn't remotely as good as the Kamino products from Jango Fett DNA, and the quality suffered. But a Jango Fett clone, even with accelerated aging, is still a tough, dangerous opponent. Of course, the Empire is also running experiments on these guys, such as the Dark Trooper project, so it might be interesting to see how someone might bring that into play.
That, of course, would make for a very interesting officer or replacement NCO. Just a thought, because the first run of Fett clones were very elite troops.
Sorry I just have to butt in real quickly. A lot of cloning was completely shut down after the Clone Wars due to a small rebellion on the Kamino cloning facilities. Most clones still in service rose the ranks and semi-trained soldiers replaced them. Also, Dark Troopers in the generic sense were usually battle droids actually. There were some Dark Troopers who were cybernetically enhanced clones in exoskeletons, but those were rare.