In general, you can use 者 for 'the person who' to describe what a person is,
For example:
反革命 Counter-revolution --> 反革命者 counter-revolutionary (the one who act against the revolution)
However, Chinese used to call them. "反革命分子" (Counter-revolutionary/ Counterrevolution elements)
Calling a group of people in the population as "elements" imply 'it is only a small minority of people within the population
Example:
反革命分子 = Counterrevolution elements (Counter-revolutionary/ people who act against revolution)
Other example:
犯罪分子 = criminal elements (people who commit crime)
反革命分子 is also called 反动分子 (the people who act against the revolution movement) or 反动派 (the group that act against the revolution movement)
动 is short for 运动
Back then if you opposed the revolution (voiced different opinions), the CPC government would treat you as 反革命思想者 (the one who have counter-revolutionary mind) and they could up the charge to 反革命分子 -- That was a serious crime in Mainland China
反动罪
现行的《中华人民共和国刑法》中無「反动罪」此罪名,但以前的刑法中存在過反革命的定义,以及因其所产生的反革命罪。
There is no "Counter-revolutionary crimes" in the current "Criminal Law of the People's Republic of China", but there had been counter-revolutionary definitions and the related counter-revolutionary crimes in the previous criminal law