ok, I guess I'll go case by case for you.
Peter I, (a homo)- construction of St. Petersburg; Baturyn; murders of Cossacks commanders (ex.Polubotok)
Catherine- destruction of Sich; institution of full serfdom in Ukraine.
Stalin- obvious.
NORTHERN WAR, SWEDES AND RUSSIAN TSAR PETER I IN BEREZHANY
The events of Northern War, caused coming of the greatest Russian tsar Peter I to Berezhany. The owner of Berezhany, magnate Sieniawski took part in this war on the side of Polish king August II and his ally, the Russian tsar against the Swedes and other Polish king Stanislaw Lieszczynski. In 1707 Peter I came to Berezhany while going from Zolkiew (Zhovkva, former Nesterov in Lviv region) to develop the strategic plans of fight against the enemy. He surveyed the castle, studied its defensive capabilities. Peter I lived in a summer hunting palace of Sieniawski in suburbian village Raj (Ray, now part of the town). The palace is preserved until nowadays, being declared as architecture monument.
In 1709 Berezhany was attacked by the detachment of A. Smigielski, the adherent of king Lieszczynski but Smigielski experienced the defeat here.
http://www.personal.ceu.hu/students/97/Roman_Zakharii/history.htm
Crimea wouldn't even be a part of Ukraine for the government to opress if not for Cathrine conquering it.
Give it 20 years. Some enterprising east europeon nation will come to conquer ukraine and they'll run back to Russia begging for help.
If not for it's Russian brothers Ukraine would speak Polish.