The word(s) "worst" appears 33 time(s) in 33 verse(s) in Quran in Mohsin Khan translation.

(11) Verily! The worst of (moving) living creatures with Allah are the deaf and the dumb, who understand not (i.e. the disbelievers).

(12) Verily, The worst of moving (living) creatures before Allah are those who disbelieve , - so they shall not believe.

(13) O Prophet (Muhammad صلى الله عليه وسلم)! Strive hard against the disbelievers and the hypocrites, and be harsh against them, their abode is Hell, - and worst indeed is that destination.

(14) The bedouins are the worst in disbelief and hypocrisy, and more likely to be in ignorance of the limits (Allah's Commandments and His Laws) which Allah has revealed to His Messenger. And Allah is All-Knower, All-Wise.

(15) They [(Yusuf's (Joseph) brothers] said: "If he steals, there was a brother of his [Yusuf (Joseph)] who did steal before (him)." But these things did Yusuf (Joseph) keep in himself, revealing not the secrets to them. He said (within himself): "You are in worst case, and Allah is the Best Knower of that which you describe!"

(16) For those who answered their Lord's Call [believed in the Oneness of Allah and followed His Messenger Muhammad صلى الله عليه و سلم i.e. Islamic Monotheism] is Al-Husna (i.e. Paradise). But those who answered not His Call (disbelieved in the Oneness of Allah and followed not His Messenger Muhammad صلى الله عليه و سلم), if they had all that is in the earth together with its like, they would offer it in order to save themselves (from the torment, but it will be in vain). For them there will be the terrible reckoning. Their dwelling-place will be Hell; and worst indeed is that place for rest.

(17) Then indeed We shall drag out from every sect all those who were worst in obstinate rebellion against the Most Gracious (Allah).

(18) Say (O Muhammad صلى الله عليه وسلم) whoever is in error, the Most Gracious (Allah) will extend (the rope) to him, until, when they see that which they were promised, either the torment or the Hour, they will come to know who is worst in position, and who is weaker in forces. [This is the answer to the question in Verse No.19:73]

(19) And they wanted to harm him, but We made them the worst losers.

(20) And when Our Clear Verses are recited to them, you will notice a denial on the faces of the disbelievers! They are nearly ready to attack with violence those who recite Our Verses to them. Say: "Shall I tell you of something worse than that? The Fire (of Hell) which Allah has promised to those who disbelieved, and worst indeed is that destination!"