This is a brief overview. For a detailed look at Estonia’s monuments in particular, see Nazi collaborator monuments in Estonia. (Originally this thread was just going to be about Estonia’s, but I decided on this summary of the overall situation instead.)
Poland, monument to Józef “Ogień” Kuraś, pogromist, traitor multiple times and nazi collaborator:
When they were building it, they did had a historians conference, but did not allowed in anyone who criticized him. Now even their own propaganda “history” institute IPN admits he was a criminal. Took them sweet time to figure, while even the fucking Home Army tried to assassinate him twice back in the days.