I've been thinking lately about how many Classic Trilogy characters show up in the Prequel era--and I don't mean the obvious ones like Obi-Wan, Palpatine, and C-3PO. Here's the ones I can think of off the top of my head--any others?

Sate Pestage
Palpatine's future dignitary (and brief successor) makes an appearance in Cloak of Deception as his aid.

Wilhuff Tarkin
Appears in Cloak of Deception as the Governor of Eriadu and in Rogue Planet as a Republic General.

Greedo (???)
In one of the most famous cut scenes, a brash young Rodian is called Greedo. It contradicts EU and is just a bad idea all around. If Greedo were as dumb as he is in Mos Eisley, he wouldn't have lived long enough to get there. I guess Lucas realized that and made a wise decision to cut it. Still, he's included for completeness.

Wuher
Appears briefly in the Aurra Sing comic. A kid in Mos Espa who's terrified by her appearance and tactics is asked his name, which turns out to be Wuher. The age and general appearance are right.

Tessek (???)
A Senator Tessek is mentioned in Cloak of Deception. I think it's either a typo for Senator Tikkes or Tessek is a common Quarren name. I can't imagine an Old Republic Senator retiring, becoming an accountant, and getting mixed up with Jabba.

Bib Fortuna
Jabba's majordomo way back when. I don't like this one, and the contradiction of EU is the least of my reasons. First, he looks different--way different. Second, he seems young in ROTJ, and this would put him in his 60s. A bit too old for the character as he appeared, I think.

Ephant Mon
Appears in Prelude to Rebellion.

Djas Puhr
Apparently appears as a slaver working for Sebulba in Scholastic's Episode One Adventures. I haven't read this, as it requires an expensive subscription.

C-3PX (EU)
Appears in the same series as Djas Puhr--and is built by Darth Maul!

Princess Leia's Bikini
Worn by Diva Shaliqua.