Karl Marx was misused by Lenin and other dictators to legitimize their so-called "dictatorships of the proletariat", while no proletariat was dictating things.
Friedrich Nietsche's idea of a Superman was liked by the Nazis.
Hugo Chavez has, not so long ago, advised people to read a work of Noam Chomsky.
And Paulo Freire has been closer to the libertarian left than many marxists want him to have been...