Shylock was initially written in as a stereotypical character, close to a state of villainy. But as the play progresses, he becomes more of a tragic figure, being cornered like an animal. Shylock is simply dubbed "the Jew," especially by everyone's favorite extrovert, Gratiano. Jessica runs off with her Christian lover, Lorenzo, deepening his wounds further.
This can attribute to the harsh treatment the Jews received during the Renaissance. At the time, lending money was the only career that Jews could attain. From the dominant Christian standpoint, money lending was considered a "sin," and this lowered the status of Jewish people even further. Even though anti-semitism has decreased in Europe, it still runs rampant and elsewhere in the world.
The influence of Shylock and Shakespearian themes have introduced the new term known as "shylocking." To label someone as a "shylock" is to call him or her a "loan shark." A "shylock", simply put, is a person who lends money at a rate that would make the patron throw the hat down and yell a series of curse words. "Shylock" has popped up in the movie Get Shorty and even "a pound of flesh" has shown up on tongues as a way of getting revenge.
In irony, though Shylock has been portrayed as the stereotype on how people viewed Jews in the day, he is a character that for a while controlled Shakespeare's pen. Whether Shakespeare was or was not anti-semitic, he could not directly portray actual injustice done on Jews because of the intense hatred that flooded through his period, save for Shylock's speech about prejudice aimed at him.
Below is a scene from a clip of 2004's The Merchant of Venice, with Al Pacino presenting Shylock's most famous speech, and possibly the most famous speech from Shakespeare's writings. Bringing the video onto this post was not as difficult as I made it out to be, as I just went to "Edit Html" which allowed the video to be set.