The word(s) "oppressor" appears 17 time(s) in 17 verse(s) in Quran in Mohsin Khan translation.

(11) "But seek, with that (wealth) which Allah has bestowed on you, the home of the Hereafter, and forget not your portion of lawful enjoyment in this world; and do good as Allah has been good to you, and seek not mischief in the land. Verily, Allah likes not the Mufsidun (those who commit great crimes and sins, oppressors, tyrants, mischief-makers, corrupters)."

(12) He said: "My Lord! Give me victory over the people who are Mufsidun (those who commit great crimes and sins, oppressors, tyrants, mischief-makers, corrupters).

(13) And to (the people of) Madyan (Midian), We sent their brother Shu'aib. He said: "O my people! Worship Allah (Alone) and hope for (the reward of good deeds by worshipping Allah Alone, on) the last Day (i.e. the Day of Resurrection), and commit no mischief on the earth as Mufsidun (those who commit great crimes, oppressors, tyrants, mischief-makers, corrupters). [Tafsir At-Tabari]

(14) And a believing man of Fir'aun's (Pharaoh) family, who hid his faith said: "Would you kill a man because he says: My Lord is Allah, and he has come to you with clear signs (proofs) from your Lord? And if he is a liar, upon him will be (the sin of) his lie; but if he is telling the truth, then some of that (calamity) wherewith he threatens you will befall on you." Verily, Allah guides not one who is a Musrif (a polytheist, or a murderer who shed blood without a right, or those who commit great sins, oppressor, transgressor), a liar!

(15) And indeed Yusuf (Joseph) did come to you, in times gone by, with clear signs, but you ceased not to doubt in that which he did bring to you: till when he died you said: "No Messenger will Allah send after him." Thus Allah leaves astray him who is a Musrif (a polytheist, an oppressor, a criminal, sinner who commit great sins) and a Murtab (one who doubts Allah's Warning and His Oneness).

(16) The recompense for an evil is an evil like thereof; but whoever forgives and makes reconciliation, his reward is with Allah. Verily, He likes not the Zalimun (oppressors, polytheists, and wrong-doers).

(17) And whomsoever Allah sends astray, for him there is no Wali (protector, helper, guardian) after Him. And you will see the Zalimun (polytheists, wrong-doers, oppressors): when they behold the torment, they will say: "Is there any way of return (to the world)?"