Oppressor (noun)

1. A person or group of people who use their power to subjugate, control, or exploit others.
2. A person or group of people who use their power to keep others in a state of subjection or hardship.

Origin:

Late middle english: from old french oppressour, from latin oppressor, from oppress- "oppressed", from the verb opprimere.

Examples:

1. The oppressors used violence to maintain their power over the oppressed.
2. The government was accused of being an oppressor for its treatment of minority groups.
3. The oppressors were eventually overthrown by the oppressed.
4. The ruling class was the oppressor of the working class.
5. The dictator was an oppressor who ruled through fear and intimidation.