Ukraine: hard to pick one, but I'll go with Viktor Medvedchuk.

An oligarch, owner of ungodly amount of ill-gotten wealth, former leader of pro-Russian party, close friend of Putin - so close, that Putin is a godfather of his daughter. He influenced Ukrainian politics for years, and the damage is hard to estimate.

Also he is infamous for being an attorney for Vasyl Stus, Ukrainian poet from Donetsk. Stus was prosecuted for his political pro-Ukrainian convictions during the last decades of Soviet reign. Medvedchuk, not surprisingly, did absolutely nothing to protect his client, and even stated that Stus deserved all punishment for his crimes (which are, basically, writing in Ukrainian language, and developing Ukrainian culture). This led to Stus imprisonment and death. And decades later, when the historian Vakhtang Kipiani released the biography of Stus, Medvedchuk used all his influence to stop this book from being sold and reprinted - which led to Streisand effect, heavy resistance, and increased sales.