you will find it quite prejudiced. Juror number ten basically sees people in two ways. They are either white and part of his "us" group, or they are a different race and belong to "them." "Us" is superior to "them" in his opinion.

Look, you know how those people lie. l don't have to tell you. They don't know what the truth is.

He follows that quote up with another sentence that is just dripping with racism.

And lemme tell you, they—(NO.5 gets up from table, turns his back to it, and goes to window.)—don't need any real big reason to kill someone either. You know, they get drunk, and bang, someone's lying in the gutter. Nobody's blaming them. That's how they are. You know what I mean? Violent!

By this point in the play, the other jurors have had it with his blatant prejudice, and the other jurors start turning their backs on juror number ten. He tries to soften his words by explaining that he has come across a few of "them" that are decent.

I've known a few who were pretty decent, but that's the exception. Most of them; it's like they have no feelings.

Act 3 really shows juror number ten as a racist bigot, but audiences are clued into his racist feelings much earlier in the play. One of the first things he says regarding the trial alerts audience members into his prejudice.

You're not going to tell us that we're supposed to believe him, knowing what he is. I've lived among 'em all my life. You can't believe a word they say. You know that.

Twelve Angry Men is a film, written by Reginald Rose, that demonstrates the effect of prejudice on a jury deliberating on a murder case. The three leading examples of such prejudice come from jurors number 4, 10, and 3.

The earliest and mildest statement of prejudice comes from Juror 4, an intelligent, well-to-do stock-broker.

Slums are breeding grounds for criminals. It's no secret children from slum backgrounds are potentially menaces to society.

As the majority of the jury begins to swing towards a not-guilty verdict, Juror 10 erupts in a diatribe of racial hatred towards minorities

Look, you know how these people lie. It's born in them . . . They don't know what the truth is! . . . This kid on trial here. His type. Well, don't you know about them? There's a danger here. These people are dangerous. They're wild.

He's finally silenced by Juror 4, who is perhaps embarrassed to hear his own earlier prejudice repeated in a much uglier and more irrational manner.

The final, and deepest example of prejudice, based on the defendant's youth, comes from Juror 3, a bellicose and sadistic man, whose brutal discipline had alienated his teen-aged son.

Rotten kids . . . You work your life out!

While I think it is possible to defend the idea that each juror is prejudiced in some way, I don't think that is what this question is steering an answer toward. I think this question is asking a reader to pick one or a few jurors that express strong prejudices. I think that jurors 3 and 10 are the best bet for this question. Juror number 3 is biased against the defendant right from the beginning of the play; however, we have to wait a bit in order to figure out exactly why. As it turns out, #3 has an issue with kids not respecting their fathers.

"I told him [my son] right out, 'I'm gonna make a man out of you or I'm gonna bust you up into little pieces trying.' When he was fifteen he hit me in the face. He's big, you know. I haven't seen him in three years. Rotten kid!"

Juror 3 is biased against the defendant because the defendant apparently doesn't respect his father either.

"Well [Eighteen is] old enough. He stabbed his own father four inches into the chest. They proved it a dozen different ways in court. They proved it a dozen different ways. Do you want me to list them?"

Juror number 10 isn't prejudiced against an age bracket. He is prejudiced against a racial bracket. He constantly refers to people of the defendant's race as "wild." Juror number 10 also uses a lot of "them" and "they" in reference to an entire racial category. In his mind, the defendant is guilty because he's not white.

"It's tough to figure, isn't it? A kid kills his father. Bing! Just like that. Well, it's the element. They let the kids run wild. Maybe it serves 'em right."

Each juror, with the exception of #8, enters the jury room with an individual prejudice. Whether it stems from a personal experience which has jaded the individual, stereotypical behavior, selfishness, arrogance, or mere indifference, each juror brings a preconceived notion of the defendant into that jury room. This creates turmoil between the individual jurors, thus enhancing the definition of prejudice in and of itself. It is only through the conflicts between them that they are ultimately able to recognize the gravity of their purpose, and put aside their 'baggage' in order to execute their Constitutional duty as best they could.

All you need to do is focus on juror 10. He is by far the most biased and prejudiced person in the play. He says: 

We don't owe him a thing. He got a fair trial, didn't he? You know what that trial cost? ....Look, we're all grown-ups here. You're not going to tell us that we're supposed to believe him, knowing what he is. I've lived among 'em all my life. You can't believe a word they say.

"I don't understand...Look, you know how those people lie...They don't know what the truth is....Human life don't mean as much to them as it does to us...Look, these people are drinking and fighting all the time, and if somebody gets killed....They don't care."

If we examine these quotes two points of prejudice emerge. First, he generalizes the poor. He even says that because he lived among them, he knows what they are all like. They cannot be trusted. It does not take an intelligent person to know that you cannot make sweeping generalizations.

Second, notice his inconsistency. He calls those who live in the slum "them."  If he lived among them, then can juror 10 be trusted? And why does he remove himself from them? In short, he is blind. 

This is a good question. There are many instances of prejudice in the play Twelve Angry Men. Some of the prejudice is subtle and some of it is very blatant. And as the play progresses the prejudice in the hearts of people becomes more explicit. Here are a few examples. 

Juror ten is by far the most prejudiced. He says some very charged things. 

We don't owe him a thing. He got a fair trial, didn't he? You know what that trial cost? ....Look, we're all grown-ups here. You're not going to tell us that we're supposed to believe him, knowing what he is. I've lived among 'em all my life. You can't believe a word they say.

Notice that he has an "us" vs. "them" mentality. So he makes certain pronouncements, simply because people live in a particular place. Generalizations, in this sense, can be very harmful.  He is even more blatant in his prejudice in the following quotes.

"I don't understand...Look, you know how those people lie...They don't know what the truth is....Human life don't mean as much to them as it does to us...Look, these people are drinking and fighting all the time, and if somebody gets killed....They don't care."

There is no question of where Juror ten stands. There are also more subtle forms of prejudice, such as when Juror four says that the offspring of people from the slums are potentially all bad. 

"The children who come out of slum backgrounds are potential menaces to society."