I honestly shouldn't have to write anything here, if you don't know who Bach is than there is a serious problem with your music education.
Bach was born on the year 1685 in Germany and is widely considered one of the greatest composers of all time, when discussions of classical music comes up you can bet that Bach, Mozart, and Beethoven will be the names mentioned. While Bach was widely appreciated for his technical skills it was not until the 19th century his compositions became more important to his fame.
Seriously though, I couldn't cover his entire history if I wanted to, and you should know who he is at least to a small extent. Wikipedia has an extremely in-depth article on him and there are tons of books written about the man.
Here is a fun song by The Residents: